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M13: Expert evidence



(1) Without restriction on the general powers in rule 5(1) and (2) (case management powers), the Tribunal may give directions as to--
(c) whether the parties are permitted or required to provide expert evidence, and if so whether the parties must jointly appoint a single expert to provide such evidence;” (FTT Rules, r.15(1)(c)).


Expert witness must produce witness statement


“In correspondence with HMRC prior to the hearing, the Company referred to a report prepared by a Dr Salhan (who holds a PhD in Mathematics) on the statistical basis underpinning HMRC’s assessment. However, Dr Salhan did not produce a witness statement and was not produced for cross-examination. Her report, therefore, was not evidence that HMRC’s methodology was statistically unsound and we have not treated it as such.” (Morrella Ltd v. HMRC [2017] UKFTT 13 (TC), §4).


Should set out the substance of his instructions


“He was also criticised for not including the full text of his instructions from HMRC, but CPR PD 3.2 (3) only requires the expert to set out the substance of his instructions, and I find that Dr Rubin did that.” (Anglian Water Services Ltd v. HMRC [2017] UKFTT 386 (TC), §83, Judge Mosedale).

Expert witness must produce witness statement

Must contain summary of instructions (or else disclosure)


"[95] CPR 35.10 (3) and (4) together provide that an expert must include within their report a summary of their material instructions but that to the extent that they have done so there is no requirement that such documents be provided by way of disclosure in the proceedings.  Only where there are reasonable grounds for considering that the statement of instructions is inaccurate or incomplete will disclosure be ordered of the documents in which the instructions are given."(Wired Orthodontics Limited v. HMRC [2020] UKFTT 290 (TC), Judge Amanda Brown)

Material instructions only

"[96] In this context it was determined by the Court of Appeal in Lucas v Barking, Havering & Redbridge NHS Trust [2004] 1 WLR 220 that the word “instruction” is to be given a wide meaning which will encompass all material supplied by the instructing party to the expert on which the expert is being asked to advise.  However, the court also confirmed that the requirement of CPR 35.10(3) is limited to “material” instructions with the consequence that it is not necessary for an expert to fully set out the detail of all instructions and information provided and a failure to do so does not therefore result in a right for the other party to seek disclosure or be permitted to question the expert at trial on the content of the documents provided to the expert.  What is required of the statement of material instructions is that they are sufficient such that the “imperative of transparency” is met by broadly ensuring that the factual basis on which the report is prepared is apparent." (Wired Orthodontics Limited v. HMRC [2020] UKFTT 290 (TC), Judge Amanda Brown)

For privilege see M6: Legal and Litigation Privilege

Must contain summary of instructions (or else disclosure)

General considerations


“[44] As we have said, a skilled person can give expert factual evidence either by itself or in combination with opinion evidence. There are in our view four considerations which govern the admissibility of skilled evidence:
(i) whether the proposed skilled evidence will assist the court in its task;
(ii) whether the witness has the necessary knowledge and experience;
(iii) whether the witness is impartial in his or her presentation and assessment of the evidence; and
(iv) whether there is a reliable body of knowledge or experience to underpin the expert’s evidence.
All four considerations apply to opinion evidence, although, as we state below, when the first consideration is applied to opinion evidence the threshold is the necessity of such evidence. The four considerations also apply to skilled evidence of fact, where the skilled witness draws on the knowledge and experience of others rather than or in addition to personal observation or its equivalent.” (Kennedy v. Cordia (Services) LLP [2016] UKSC 6)

Necessary or reasonably required


“…the court must ask itself the following important questions: 

(a) The first question is whether, looking at each issue, it is necessary for there to be expert evidence before that issue can be resolved. If it is necessary, rather than merely helpful, it seems to me that it must be admitted.

(b) If the evidence is not necessary, the second question is whether it would be of assistance to the court in resolving that issue. If it would be of assistance, but not necessary, then the court would be able to determine the issue without it (just as in Mitchell the court would have been able to resolve even the central issue without the expert evidence).

(c) Since, under the scenario in (b) above, the court will be able to resolve the issue without the evidence, the third question is whether, in the context of the proceedings as a whole, expert evidence on that issue is reasonably required to resolve the proceedings." (British Airways plc v. Spencer [2015] EWHC 2477 (Ch), §21).

Reason for expert evidence: the product of special expertise which the tribunal does not possess/not its function to apply


“An expert’s evidence of opinion is admissible because it is the product of a special expertise which the tribunal does not possess, or even if it does, which is not its function to apply (Hoyle).” (Deloitte LLP v. HMRC [2016] UKFTT 479 (TC), §22(2)).

Role is to provide material on which a court can form its own conclusions


“[49]...Thus, while on occasion in order to avoid elusive language the skilled witness may have to express his or her views in a way that addresses the ultimate issue before the court, expert assistance does not extend to supplanting the court as the decision-maker. The fact-finding judge cannot delegate the decision-making role to the expert.” (Kennedy v. Cordia (Services) LLP [2016] UKSC 6)


“It is the duty of an expert witness to provide material on which a court can form its own conclusions on relevant issues. On occasions that may involve the witness expressing an opinion about whether, for instance, an individual suffered from a particular condition or vulnerability. The expert witness should be careful to recognise, however, the need to avoid supplanting the court’s role as the ultimate decision-maker on matters that are central to the outcome of the case.” (Pora v. The Queen [2015] UKPC 9, §24).

Unsubstantiated conclusions are worthless


“[48] An expert must explain the basis of his or her evidence when it is not personal observation or sensation; mere assertion or “bare ipse dixit” carries little weight, as the Lord President (Cooper) famously stated in Davie v Magistrates of Edinburgh 1953 SC 34, 40. If anything, the suggestion that an unsubstantiated ipse dixit carries little weight is understated; in our view such evidence is worthless.” (Kennedy v. Cordia (Services) LLP [2016] UKSC 6)

General considerations

Reliable body of knowledge or experience


““Before admitting the opinion of a witness into evidence as expert testimony, the Judge must consider and decide two questions. The first is whether the subject matter of the opinion falls within the class of subjects upon which expert testimony is permissible. This first question may be divided into two parts: (a) whether the subject matter of the opinion is such that a person without instruction or experience in the area of knowledge or human experience would be able to form a sound judgement on the matter without the assistance of witnesses possessing special knowledge or experience in the area and (b) whether the subject matter of the opinion forms part of a body of knowledge or experience which is sufficiently organised or recognised to be accepted as a reliable body of knowledge or experience, a special acquaintance with which of the witness would render his opinion of assistance to the Court”…I accept that what was said in Bonython was a correct statement of the law.” (Anglian Water Services Ltd v. HMRC [2017] UKFTT 386 (TC), §94, Judge Mosedale quoting R v Bonython [1984] SASR 45).


Outside generally recognised fields, it is necessary to establish the field exists


“[55] "A party seeking to lead a witness with purported knowledge or experience outwith generally recognised fields would need to set up by investigation and evidence not only the qualifications and expertise of the individual skilled witness, but the methodology and validity of that field of knowledge or science.”

[56] We agree with that proposition, which is supported in Scotland and in other jurisdictions by the court’s refusal to accept the evidence of an expert whose methodology is not based on any established body of knowledge.” (Kennedy v. Cordia (Services) LLP [2016] UKSC 6)

How a third person could be expected to act (admissible) v. how a third person did act (inadmissible)


“The Judge in [Altus Group UK Ltd v Baker Tilly Tax and Advisory Services Ltd [2015] EWHC 12 (Ch)] did appear to accept, however, that it was possible for an expert witness to give evidence about the typical behaviour of a third person. In my view, there is a very narrow line between giving evidence how about how a person could be expected to act in given circumstances, and making inferences as to how they did act, and if either expert slipped from one to the other, the Tribunal is not misled.”  (Anglian Water Services Ltd v. HMRC [2017] UKFTT 386 (TC), §98, Judge Mosedale).

Reliable body of knowledge or experience

Expertise: acquired by study or experience


““The second question is whether the witness has acquired by study or experience sufficient knowledge of the subject to render his opinion of value in resolving the issue before the Court.”…I accept that what was said in Bonython was a correct statement of the law.” (Anglian Water Services Ltd v. HMRC [2017] UKFTT 386 (TC), §94, Judge Mosedale quoting R v Bonython [1984] SASR 45).


Consider relative expertise of witnesses


“I consider that Dr Rubin could evidence on economic theory and, because the regulator would be seeking to replicate an outcome that a free market would generate (both experts were agreed on this and also see §52), economic theory was relevant to what regulator would have done. So, to some extent, I accept that Dr Rubin could give an expert opinion on (2) because he was an expert economist, however, I accept Mr Rivett’s point that only Dr Koboldt was an expert on regulatory economics, and therefore that Dr Koboldt should be in a position, unlike Dr Rubin, to give evidence on what a regulator would do in practice.” (Anglian Water Services Ltd v. HMRC [2017] UKFTT 386 (TC), §105).


Direct experience more valuable and reliable than indirect experience


“Experience and expertise may have a number of sources. What might be termed as direct “field” experience may usually be the most valuable, and the 10 most reliable. But especially where (as here) the expertise called for is in identifying characteristics of a given market, previous experience in analysing that market is not to be disparaged or thought invalid. Of course there is the danger that an expert may come to be regarded as such simply because he has said the same thing on different occasions or clings to his views with professional tenacity.” (Edgeskill Limited v. HMRC [2014] UKUT 38 (TCC), §180, Hildyard J).


Past experience of giving expert evidence may be a factor


“However, I do not think it wrong, by way of assessing the issue, to bear in mind the dozen or more occasions on which Mr Fletcher had previously given evidence of the grey market to Tribunals, though it is also right to recognise that his expertise has been questioned by some (described not incorrectly by the Commissioners as “a small minority”).” (Edgeskill Limited v. HMRC [2014] UKUT 38 (TCC), §180, Hildyard J).


Challenge to expertise should be made prior to witness giving evidence


“Ground 4 of the appeal is that the FTT erred in accepting Mr Fletcher’s opinions as expert evidence and should have instead rejected it altogether as being that of a non-expert…I accept that the Appellant should have required a ruling on its objection; and then either appealed, reserved a right to appeal subsequently, or abandoned (or be taken to 35 have abandoned) that objection. But the Commissioners themselves could also have pressed for a ruling.” (Edgeskill Limited v. HMRC [2014] UKUT 38 (TCC), §§167…170, Hildyard J).

Expertise: acquired by study or experience

Duties and independence of expert


“[52] The duties and responsibilities of expert witnesses in civil cases include the following:
1. Expert evidence presented to the court should be, and should be seen to be, the independent product of the expert uninfluenced as to form or content by the exigencies of litigation.
2. An expert witness should provide independent assistance to the court by way of objective unbiased opinion in relation to matters within his expertise. An expert witness in the High Court should never assume the role of an advocate.
3. An expert witness should state the facts or assumption on which his opinion is based. He should not omit to consider material facts which could detract from his concluded opinion.
4. An expert witness should make it clear when a particular question or issue falls outside his expertise.
5. If an expert’s opinion is not properly researched because he considers that insufficient data is available, then this must be stated with an indication that the opinion is no more than a provisional one. In cases where an expert witness who has prepared a report could not assert that the report contained the truth, the whole truth and nothing but the truth without some qualification, that qualification should be stated in the report.
6. If, after exchange of reports, an expert witness changes his view on a material matter having read the other side’s expert’s report or for any other reason, such change of view should be communicated (through legal representatives) to the other side without delay and when appropriate to the court.
7.  Where expert evidence refers to photographs, plans, calculations, analyses, measurements, survey reports or other similar documents, these must be provided to the opposite party at the same time as the exchange of reports.” (Kennedy v. Cordia (Services) LLP [2016] UKSC 6, citing The Ikarian Reefer [1993] 2 Lloyd’s Rep 68).


Duty to disclose any potential conflict of interest


“In my view, the burden was fairly and squarely on the Defendant, in particular on Dr Molyneux who was to be the Defendant's key (in the event, sole) expert witness at the trial, to state frankly, with adequate particulars, the nature and extent of any connection between Dr Barker [the defendant] and Dr Molyneux.” (EXP v. Barker [2015] EWHC 128 (QB), §50 – claim for medical negligence).


Interest in the proceedings not an automatic bar: is the person willing and able to give independent evidence?


“The following principles emerge from these authorities: -
i) It is always desirable that an expert should have no actual or apparent interest in the outcome of the proceedings.
ii) The existence of such an interest, whether as an employee of one of the parties or otherwise, does not automatically render the evidence of the proposed expert inadmissible. It is the nature and extent of the interest or connection which matters, not the mere fact of the interest or connection.

iv) The decision as to whether an expert should be permitted to give evidence in such circumstances is a matter of fact and degree. The test of apparent bias is not relevant to the question of whether or not an expert witness should be permitted to give evidence.
v) The questions which have to be determined are whether (i) the person has relevant expertise and (ii) he or she is aware of their primary duty to the Court if they give expert evidence, and willing and able, despite the interest or connection with the litigation or a party thereto, to carry out that duty.” (Armchair Passenger Transport Limited v. Helical Bar plc [2003] EWHC 367 (QB), §29, Nelson J)


Interest not sufficient to exclude evidence, but does affect weight


“vii) If the expert has an interest which is not sufficient to preclude him from giving evidence the interest may nevertheless affect the weight of his evidence.” (Armchair Passenger Transport Limited v. Helical Bar plc [2003] EWHC 367 (QB), §29, Nelson J)


HMRC employees


“Being an HMRC employee does not bar Dr Rubin  from being an expert witness on behalf of HMRC.  The question is whether he understood his duty to the Tribunal and actually gave an opinion uninfluenced by partisan considerations…” (Anglian Water Services Ltd v. HMRC [2017] UKFTT 386 (TC), §83, Judge Mosedale – on the facts held that the witness did understand his duty).


“Mr Wheeler is an officer of the commissioners’ Share and Assets Valuation Office and a member of the Business Valuation Faculty of the Royal Institution of Chartered Surveyors.  As such, Mr Wheeler is not an independent expert witness and indeed he had a minor involvement in the handling of this case; although Mr Wheeler is clearly well versed in valuation matters, his views are put forward on behalf of the commissioners and his opinions must be seen as those of an officer whose primary duty is to his employers.” (Dyer v. HMRC [2013] UKFTT 691 (TC), §33).




“Where a medical practitioner such as Dr Molyneux has played a relatively prominent part as mentor of another practitioner's career, the bond may well have a very lasting effect, and it is imperative that the connection, even if well in the past, should be disclosed if the mentor is to be put forward as an independent expert witness whose evidence would benefit the person who had been under his or her tutelage.” (EXP v. Barker [2015] EWHC 128 (QB), §54).


Taxpayer’s adviser


“No expertise in the field of statistics was claimed for Mr Man and Mr McNicholas accepted (as he had to) that, since Mr Man was the Company’s adviser, he was not sufficiently independent to give expert evidence in any event. We have disregarded Mr Man’s opinion evidence. However, we have considered for ourselves whether the method HMRC used to make the assessments was so unsustainable that it had to be set aside or replaced by another method.” (Morrella Ltd v. HMRC [2017] UKFTT 13 (TC), §3).

Duties and independence of expert

Experts must constantly remind themselves of their duties


"[284] Experts should constantly remind themselves through the litigation process that they are not part of the Claimant’s or Defendant’s “team” with their role being the securing and maximising, or avoiding or minimising, a claim for damages. Although experts always owe a duty to exercise reasonable skill and care to those instructing them, and to comply with any relevant professional code, as CPR 35.3 expressly states they have, at all times, an overriding duty to help the Court on matters within their expertise. That they have a particular expertise and the court and parties do not (save in some professional negligence claims) means that significant reliance may be placed on their analysis which must be objective and non-partisan if a just outcome is to be achieved in the litigation." (Muyepa v. Ministry of Defence [2022] EWHC 2648 (KB), Cotter J)

Experts must constantly remind themselves of their duties

True and complete professional opinion (importance of completeness)


"[290] The words “and complete” are there for a purpose.  As set out above CPR 35 PD 2.3 provides that experts should consider all material facts, including those which might detract from their opinions and CPR 35 PD 3.6(6) refers to the need to deal with any range of opinions on the matters covered within the report.  The court should receive a comprehensive, objective analysis; including whether an alternative view to that held by the author is tenable.  An expert must not solely pick out pieces of evidence or entries in documents which provide support for the conclusion he/she has reached whilst not addressing material that points, or may point, the other way. Where there is a contrary interpretation, analysis or view it should be set out in the report and it is a breach of the duties owed to the Court by an expert to leave such issues to be raised by an expert instructed by the other party." (Muyepa v. Ministry of Defence [2022] EWHC 2648 (KB), Cotter J)

True and complete professional opinion (importance of completeness)

Must notify the parties and court of any change of view without delay (and before entering witness box)


"[291] The sixth of the Ikarian Reefer principles and CPR 35 PD 2.5 cover the position where an expert has changed his or her view arising as a result of matters that have occurred after they have prepared a written report (or joint report). Importantly this includes a change of opinion during a trial. By way of example if as a result of lay witness evidence an expert’s view has changed he/she should communicate this (through the legal representatives who have instructed him/her) to the other side without delay and when appropriate to the court. An expert should not step into a witness box having changed his /her view without having made this plain beforehand. If the change of opinion is properly communicated it may alter the need for or extent of evidence to be given.


[302(d)] Ms Kerby entered the witness box not having advised the Court of her revised view after the Claimant and Mrs Muyepa had given evidence.  Ms Kerby realised that the figures she had set out in her reports were unsustainable in light of the evidence given by the Claimant and his wife but she did provide set out any recalculation. By way of example when Ms Kerby was alerted to the hours that Mrs Muyepa worked (and also that she had moved to stay in a house a 45 minute drive away) she formed the view that the hours of care she had estimated for past and future care were unrealistic. As she said during cross-examination “I realise the care level is affected big time” yet she had provided no recalculations When I explained how unsatisfactory this was there was an “on the hoof” recalculation during re-examination which was difficult to follow at times and obviously unsatisfactory.  A court will, if time is available, give an opportunity for an expert to provide a revised report/recalculation. Here the evidence of the Claimant was given 10 days (and that of his wife 5 days) before Ms Kerby gave her evidence and there was ample time to provide a revision to the opinion previously provided." (Muyepa v. Ministry of Defence [2022] EWHC 2648 (KB), Cotter J)

Must notify the parties and court of any change of view without delay (and before entering witness box)
Presumption that relevant evidence should be admitted

Presumption that relevant evidence should be admitted


“The parties were in agreement that, as set out by Lightman J in Mobile Export 365 Ltd v Commrs for HMRC [2007] EWHC 2664 (Admin), the key issue on applications for admissibility was relevance, and that there was a presumption that all relevant evidence should be admitted unless there were compelling reasons to the contrary. In HMRC v Atlantic Electronics Ltd the Court of Appeal in dealing with an appeal from the Upper Tribunal (“UT”), endorsed this approach noting at [31] that the UT in that case had also analysed the balance of prejudice to each party and at [30] and [71] that the tribunal had far more general powers to admit than under the Civil Procedure Rules (“CPR”). The FTT’s decision in Omagh Minerals Limited v Commrs for HMRC [2015] UKFTT 681 (TC), is a relatively recent example of the application of the above approach in relation to expert evidence.” (Deloitte LLP v. HMRC [2016] UKFTT 479 (TC), §7).


“The principle relied upon by HMRC from Atlantic (that relevant evidence should be admitted unless there is a compelling reason not to) are no less applicable outside of the area of statements which explain the background to something which is a matter of public record. To the extent there is opinion evidence this may be taken into account and may be disregarded by the Tribunal. As pointed out by the FtT in Megantic at [38] if the evidence is not given by an expert or given by an expert but safeguards not observed this may go to the weight of the evidence. But, neither of those matters compels a conclusion that evidence, if it is relevant, should not be admitted.” (Belgravia Trading Co Ltd v. HMRC [2014] UKFTT 31 (TC), §31, Judge Raghavan).

Evidence going directly to the question before the tribunal


No blanket restriction


“Although in former years it was said that experts should not give opinions on the “the very issue which the court has to decide”, that restriction is no longer in force, at least in civil actions: see Barings plc (in liq) v Coopers & Lybrand  [2001] Lloyd’s Rep (Bank) 85 at para 54 per Evans-Lombe J and the cases there cited. However it is not for experts to attempt to make findings of fact. Instead they should express their opinion on the area in which they have their expertise on the basis of assumed facts which should be clearly identified and stated in their expert report.” (JP Morgan Chase Bank v Springwell [2006] EWHC 2755 (Comm), §21).


Statement about what the domestic law is is not evidence


“In my judgment the question of whether such materials should be admitted, and the presumption that relevant evidence must be admitted is not on point; issues of what the law is, are plainly not matters of evidence. The Tribunal Rules, which draw a distinction between evidence and submissions refer to expert evidence and the flexibility to admit or exclude under Rule 15(2) is in relation to admission or exclusion of evidence. The rules do not need to deal with the admission or exclusion of law because they do not envisage that evidence will be relevant to proving what the law is.” (Deloitte LLP v. HMRC [2016] UKFTT 479 (TC), §50).

Nor is statement applying the law


“Category 2) includes any statement e.g. that a particular Handbook provision applies, or that a particular person is required or permitted to do something under the relevant regulatory provision, or that there is a legally valid contract or the effect of it. The same analysis - that such statements are not evidence – applies.” (Deloitte LLP v. HMRC [2016] UKFTT 479 (TC), §51).

Opinions based on inadmissible views on the law also inadmissible


“As regards (3) (and indeed 1) and 2))  as indicated by the approach of the High Court in JP Morgan referring to what was said by the High Court in Barings and the Supreme Court in Kennedy,  there is nevertheless  a discretion to allow a  report which contains such matters to be admitted even if it expresses a view on whether and how certain legal tests are fulfilled on the basis that the court or tribunal can be trusted with the task of making its own mind up on the issue. But, in my view it is relevant to draw a distinction between opinions on the issue for the court or tribunal whose foundation is built on matters which are outside the tribunal’s expertise (the value for which will be for the tribunal – having examined the underlying explanation of facts and reasoning to consider what it makes of the ultimate opinion) and opinions whose foundation itself rests on legal matters which are properly for the tribunal to reach a conclusion on with the benefit of evidence of the relevant facts and legal submissions.” (Deloitte LLP v. HMRC [2016] UKFTT 479 (TC), §52).

Evidence going directly to the question before the tribunal

Not a judge of facts and not an advocate


"[280] I doubt either Ms Kerby or Mr Craggs would be anxious to relive their experience of giving evidence. However I have limited sympathy for either in this regard. They acted at times as advocate for the Claimant and both at times presented partisan views to the court and, in my view, in so doing neglected their duties as independent experts.

[281] The very significant edifice of damages constructed within the schedule was built with significant reliance upon the evidence of Ms Kerby and crumbled significantly as the case progressed even on the assumption that the Claimant’s evidence was largely reliable.

[282] At times Mr Craggs adopted the twin roles of expert and Judge of the facts (his findings being favourable to the Claimant).


[310]  Ms Ferrie was a balanced and helpful expert and I have no hesitation in preferring her analysis of the degree of function revealed on the surveillance and social media clips." (Muyepa v. Ministry of Defence [2022] EWHC 2648 (KB), Cotter J)

Not a judge of facts and not an advocate

When expert evidence is required


Necessary in relation to common practice in specialist areas


“We have considered what weight, if any, to give Mr Savage’s unchallenged evidence that he believed because all the relevant share issues by Perenco were listed on the London Stock Exchange Perenco would have treated the shares as being issued in the UK regardless of the fact that some of the shares may have been issued to overseas shareholders…[H]is evidence on this point seemed to be non-independent expert opinion evidence rather than evidence of fact within his own knowledge. Evidence of common practice in a specialist area would usually be given by an expert witness. For these two reasons we attach no weight to Mr Savage’s evidence on this point. If Perenco wished to rely upon evidence of common practice in this specialised field it should have called an independent expert to give evidence, but it chose not to do so.” (Perenco Holdings v. HMRC [2015] UKFTT 0065 (TC), §123).


“Save in cases of solicitors' negligence where the Court of Appeal has said that it is unnecessary (see Brown v Gould & Swayne [1996] 1 PNLR 130 ) and the sort of exceptional case summarised at paragraph 6-009 – 6–011 of Jackson & Powell, Sixth Edition, which does not arise here, it is standard practice that, where an allegation of professional negligence is to be pleaded, that allegation must be supported (in writing) by a relevant professional with the necessary expertise. That is a matter of common sense: how can it be asserted that act x was something that an ordinary professional would and should not have done, if no professional in the same field had expressed such a view?” (Pantelli Associates Ltd v. Corporate City Developments Number Two Ltd [2010] EWHC 3189 (TCC), §17).


“In passing I note that there is no expert evidence from a solicitor experienced in this field of practice that it is the duty of a solicitor to go over a banking report and tell the recipient what is commercially significant about it. I was told that no solicitor expert evidence was provided because it was thought that the court would have the necessary expertise. Quite why, I do not know. Judges are unlikely to have much had experience of this sort of thing. Whilst they are equipped to decide points of law, practice in a field of expertise is something quite different.” (Guild (Claims) Ltd v. Eversheds (a firm) [2000] All ER (D) 986, §33).




“…the Judge ought to have formed his own assessment of the alternative case and was not able to decline to do so on the basis that he did not have expert evidence to help him.” (HMRC v. CCA Distribution (in administration) Ltd [2015] UKUT 513 (TCC), §118, Morgan J and Judge Herrington).


“It is true that the FTT was required to invest the reasonable man for these purposes with the characteristic of being a reasonable businessman with ordinary competence, but in our judgment a reasonable businessman with ordinary competence is not so egregious or specialist a variant of the anthropomorphic conception of justice that the FTT needed evidence of the normal characteristics of legitimate trade in the grey mobile phone market, or any other expert evidence, in order fairly and justly to apply the required impersonal standard.” (S&I Electrical PLC v. HMRC [2015] UKUT 162 (TCC), §65).


But even in S&I Electrical plc


“In our judgment, the FTT erred in law in taking into account in its legal reasoning in relation to its alternative conclusion at paragraph [85] of the Second FTT Decision the further investigations mentioned at paragraph [215] of the First FTT Decision, because there were no grounds for it to do so. Those further investigations were not raised with S&I’s witnesses and were not the subject of any evidence, at least no such evidence was referred to. In our judgment, in the circumstances, there can have been no reasonable and proper basis for advancing them and relying upon them.” (S&I Electrical plc v. HMRC [2015] UKUT 162 (TCC), §71, Asplin J and Judge Walters QC).


“It seems to us that the absence of any evidence before the FTT as to the characteristics of legitimate grey mobile phone market trading makes it impossible for S&I to substantiate its proposition that all of the ‘five indicia’ are consistent with legitimate transactions.” (S&I Electrical plc v. HMRC [2015] UKUT 162 (TCC), §79, Asplin J and Judge Walters QC).


Commercial practice


“He referred me to what Judge Cornwall-Kelly said in a case called HG Purser Limited v Revenue and Customs where on the substantive hearing, indeed, the FTT said at in its conclusions at paragraph [154]: "... that there has been no adequate evidence before us of what was normal commercial practice in this type of trade by a small trader in the grey market. Mr Fletcher's evidence, valuable up to a point, does not on his own admission fill this gap and we are lacking direct evidence except from Mr Purser of the matter." (Mr Purser being a director of the trader in that case)” (HMRC v. IA Associates Ltd [2013] EWHC 4382 (Ch), §48, Nugee J).


“[the taxpayer] suggested in his written submission on no case to answer that HMRC ought to call expert evidence of what arrangements would be commercial. But it seems to me that such evidence would be called in a vacuum unless called to rebut evidence from the appellant that what it had done was commercial.” (Massey and Massey t/a Hilden Park Partnership v. HMRC [2013] UKFTT 391 §§34).


Industry practice


“In particular, Mr Rees criticised the findings of the FTT, at [113] – [114] to the effect that a pensions administrator would “normally” and “perhaps invariably” exercise its discretion in accordance with a statement of wishes, and that it was “virtually inevitable” that Mrs Staveley’s wishes would be honoured…We consider that the FTT was wrong to rely on what appears to have been its own perception. There was no evidence before the FTT as to the general practice of administrators of the AXA PPP, or the practice of scheme administrators generally. The FTT was not entitled to make a finding contrary to such evidence that it did have, namely the terms of the transfer-in application in respect of the AXA PPP itself on which discretion was conferred on the scheme administrator.” (HMRC v. Personal Representatives of Staveley [2017] UKUT 4 (TCC), §§71…72).


“Accordingly at this stage it cannot be ruled out at this point that industry practice on characteristics of insurance agents and brokers is irrelevant and that evidence on this point may in principle assist the court at the final hearing. There being no compelling reason to exclude such evidence having considered the prejudice to the parties I see no bar to the appellant, it if wishes, pursuing an argument that the practice is relevant and putting forward evidence on that issue.” (Deloitte LLP v. HMRC [2016] UKFTT 479 (TC), §61).


Alleging document forged


“That a note was not an accurate record of what was said (itself not easy to prove) would not, of course, prove forgery; the writer could have misheard or misunderstood what was said or may have deliberately written a false note at the time. Given that I cannot regard the evidence of RJD1, Martin or RJD2 on the one side or Mr Deville's evidence on the other as reliable, I would ordinarily here have needed to lean in part on textual analysis (for example, for obvious anachronisms) and perhaps heavily also on professional forensic evidence as to handwriting, paper, pencil and ink analyses. Remarkably, there is no forensic evidence from either side…The Defendants' explanation for its absence, based only on instructions to Counsel rather than on evidence, was that such forensic evidence could not help. But if a whole page is later rewritten then, as it seems to me, there may be a detectable difference as to the handwriting, paper, ink or pencil between that whole page and its alleged contemporaries. If, though, parts of a page are deleted, a deletion may, one might think, leave some trace, as might also what had originally been there, and, again, there may be detectable differences as to handwriting, pencil or ink between the altered passage and its neighbours. It is not for me to say that forensic evidence would have helped; all I say is that I would need evidence before I could reliably conclude that it could not and I regard it as little short of irresponsible on the Defendants' part to make the serious allegations which they do without at least producing expert evidence that forensic examination would have been pointless…The Claimants' explanation for there being no forensic evidence from them is that it was for the Defendants to make their case on forensic evidence and that, as the Defendants never did, there was no need for the Claimants to meet it. That, though not irresponsible, is at least short sighted.” (Daniels v. Deville [2008] EWHC 1810 (Ch), §§164 – 166).

When expert evidence is required

When expert evidence not required


Disproportionate to amount at stake


“The dispute concerns an amount of less than £1,000.  Even taking into account future importations, it would take a long time for RJS to recover the costs of appointing a single joint expert.  In our judgment it was a disproportionate expense, given the nature of the issue in dispute and the amounts at stake, again even taking into account future importations.” (RJS Electronics Ltd v. HMRC [2016] UKFTT 77 (TC), §21).


Delay and cost outweigh the limited value of the expert evidence


“Although I accept that a person can have expertise in relation to financial markets I agree with Mr Afzal that it would be unlikely that he could comment with authority on every possible strategy that a financial trader could adopt. Even if this were not the case, it does not necessarily follow that if an expert has not encountered the strategy utilised by Mr Gill it could not be trading or trading commercially…Having carefully considered the submissions, while recognising that expert evidence is potentially relevant, I have come to the conclusion that, on balance, given the inevitable delay and cost associated with the provision of such evidence particularly if it were necessary to instruct two (or more) experts, which, for the reasons above, may be of limited value and assistance to the Tribunal in any event, it would be disproportionate to direct that expert evidence be admitted.” (Gill v. HMRC [2017] UKFTT 597 (TC), §§14…15, Judge Brooks).

When expert evidence not required

Quasi-expert evidence


Must have no potential conflict of interest


“First, I agree with Mr Furness’ revised position: these proposed new BBC witnesses are not “experts” or even “quasi-experts”.  In civil claims experts must have “no potential conflict of interest”, see the “Guidance for the Instruction of Experts in Civil Claims” published by the Civil Justice Council in August 2014 at paragraph 16(e) and PD35 paragraph 9(b).  Although that guidance, and the related CPR rules, do not apply directly to the FTT, in Chandanmal v HMRC [2012] UKFTT 188 (TC) at [10] Judge Mosedale said that there is no reason why the Tribunal would not follow the same approach, and I agree.” (Paya Ltd and Tim Wilcox Ltd v. HMRC [2016] UKFTT 660 (TC), §254).

Quasi-expert evidence

Excluding expert evidence


Challenge to independence should be raised as early as possible


“iii) Where the expert has an interest of one kind or another in the outcome of the case, the question of whether he should be permitted to give evidence should be determined as soon as possible in the course of case management.” (Armchair Passenger Transport Limited v. Helical Bar plc [2003] EWHC 367 (QB), §29, Nelson J)


“It is clear from Armchair Passenger Transport Ltd v Helical Bar Plc [2003]  EWHC 367 (QB) per Nelson J that it is best practice to challenge independence at an early stage in the litigation because a late but successful challenge deprives the other party of the chance to obtain expert evidence from different expert.” (Anglian Water Services Ltd v. HMRC [2017] UKFTT 386 (TC), §80, Judge Mosedale).


Expressing opinions on matters of fact which do not require expert knowledge to evaluate: question of proportionality


“Insofar as an expert's report does no more than opine on facts which require no expertise of his to evaluate, it is inadmissible and should be given no weight on that account. But, as the judge also observed, there is nothing to be gained, except in very clear cases, from excluding or excising opinions in this category. I agree with what he said in para 117 of his judgment: "Such an exercise is unnecessary and disproportionate especially when such statements are intertwined with others which reflect genuine expertise and there is no clear dividing line between them. In such circumstances, the proper course is for the whole document to be before the court and for the judge at trial to take account of the report only to the extent that it reflects expertise and to disregard it in so far as it does not.”” (Hoyle v. Rogers [2014] EWCA Civ 257, §53).


“Expert reports are not rendered inadmissible because they refer to legislation, matters of law or indeed the very issue before the court or tribunal.  Tribunal panels (who are not lay finders of fact) can be credited with the ability to distinguish between inadmissible / admissible matters in a report and to know that they have to reach their own view on the legal question before them…Even if reports contain inadmissible expert evidence of fact they can be admitted and should be admitted without requiring excision particularly if the admissible / inadmissible evidence of fact is intertwined. (JP Morgan Chase Bank, and  Kennedy)” (Deloitte LLP v. HMRC [2016] UKFTT 479 (TC), §22).

Statements that are unambiguously of no assistance to the Tribunal excluded

“As to the appellant’s argument that the law is intertwined with other evidence and the guidance in  Hoyle  that where inadmissible statements appear in a report excision is not appropriate this concern does not appear to me be on point on the facts of this application. The guidance in Hoyle acknowledged the difficulty of making judgments as to the usefulness to the court of the expert’s expertise to evidence of fact – in that context it could well be seen that such judgments would better be left to after the hearing having had the benefit of hearing from the witness and their answers in cross-examination. That is not the situation in relation to matters of law where there is no such ambiguity as to the level of assistance the statement will offer… If the report is admitted the task of disentangling what conclusions of the witness rest on contested legal matters which are not going to be of value but which will instead require focussed legal submissions and what rest on other matters falls to the tribunal panel at and after the hearing whereas it would in my view assist the tribunal far more if this work was done at the outset. Although this will involve some prejudice to the appellant in particular in terms of the additional time and cost that is outweighed in my view by the resulting benefit of putting the tribunal in a far better position to deal with appeal fairly and justly at the substantive hearing.” (Deloitte LLP v. HMRC [2016] UKFTT 479 (TC), §71).

Excluding expert evidence

Joint reports


No requirement to have instructions before agreeing joint report

"[39] It has been suggested in this case that the party through his solicitor is entitled to require the expert to take instructions from the client before signing any joint statement and to make no agreement unless specifically authorised to do so. It was submitted that the parties do not put their case in the hands of an expert to settle the case. That latter submission is a correct statement of the usual position, but that submission is not relevant to the meetings of experts ordered by the Court. The purpose of those meetings is not to achieve a settlement of the proceedings or to produce agreements binding on the parties...

[40]...Before the court will allow the evidence to be adduced, it is to be refined by the experts as far as possible.  It is not for the parties to tell the experts what opinions they are allowed to hold.  The duty owed by the experts to the court is to express in their joint statement and in their reports to the court the views which they themselves honestly hold. It is well understood that after giving his initial privileged advice to the party to the litigation an expert may honestly change his opinion either as a result of further research and thought or as a result of discussions with other experts. If he does so change his mind, he should record that change of mind either in the joint statement or in his report or, if necessary, in a supplemental report, bearing in mind that those documents will eventually become the basis of his sworn testimony. …

[41] ... The party to the litigation cannot properly tell the expert what evidence he is to give under oath in court, nor can he tell the expert what opinion to express in documents produced by him as a condition of the party being allowed to adduce that evidence...

[42] Some confusion of thought may arise when, as in the present case, the expert is a quantity surveyor given the task of expressing opinions about the amount of the sums claimed. However, just as with other experts, when they meet at an experts' meeting ordered by the court, unless they receive express instructions giving them special additional authority, they are not aiming at reaching agreements binding on the parties. Their objective is to express opinions, agreed if possible, as to the value of work done or not done, or of defective work, or the value of a freehold or whatever is in issue. Any agreements will be admissible in evidence but not as agreements binding the parties. Sometimes, the parties agree, either before or after the experts' meetings, that any agreements made by the experts will be binding on the parties, but that is a matter separate from the fact that the joint statement of the experts made after the experts' meeting is open but not binding.” (Robin Ellis Ltd v Malwright Ltd (1999)  68 ConLR 121)

Lawyers may identify issues to be considered but should not be involved in negotiating or drafting save in exceptional circumstances

[17] Mr Mort rightly complained that it was quite inappropriate for independent experts to seek input from their client's solicitors into the substantive content of their joint statement or, for that matter, for the solicitors either to ask an expert to do so or to provide input if asked, save in the limited circumstances referred to in paragraph 13.6.3 of the TCC Guide, which states that:

"Whilst the parties' legal advisers may assist in identifying issues which the statement should address, those legal advisers must not be involved in either negotiating or drafting the experts' joint statement.
Legal advisers should only invite the experts to consider amending any draft joint statement in exceptional circumstances where there are serious concerns that the court may misunderstand or be misled by the terms of that joint statement.
Any such concerns should be raised with all experts involved in the joint statement."

This is consistent with the Practice Direction to Part 35, which at paragraph 9 makes clear that:

(1) The role of the legal representatives in expert discussions is limited to agreeing an agenda where necessary and, whilst they may attend the discussions if ordered or agreed, they must not intervene and may only answer questions or advise on the law.
(2) Experts do not require the authority of the parties to sign a statement, which should be done at the conclusion of the discussion or as soon thereafter as practicable and in any event within 7 days.

[18] What happened here was, I agree, a serious transgression and it is important that all experts and all legal advisers should understand what is and what is not permissible as regards the preparation of joint statements. To be clear, it appears to me that the TCC Guide envisages that an expert may if necessary provide a copy of the draft joint statement to the solicitors, otherwise it would not be possible for them to intervene in the exceptional circumstances identified. However, the expert should not ask the solicitors for their general comments or suggestions on the content of the draft joint statement and the solicitors should not make any comments or suggestions save to both experts in the very limited circumstances identified in the TCC Guide. That is consistent with the fact that any agreement between experts does not bind the parties unless they expressly agree to be so bound (see Part 35.12(5)). There may be cases, which should be exceptional, where a party or its legal representatives are concerned, having seen the statement, that the experts' views as stated in the joint statement may have been infected by some material misunderstanding of law or fact. If so, then there is no reason in my view why that should not be drawn to the attention of the experts so that they may have the opportunity to consider the point before trial. That however will be done in the open so that everyone, including the trial judge if the case proceeds to trial, can see what has happened and, if appropriate, firmly discourage any attempt by a party dissatisfied with the content of the joint statement to seek to re-open the discussion by this means." (BDW Trading Ltd v. Integral Geotechnique (Wales) Ltd [2018] EWHC 1915 (TCC))

"[83] On the basis of this review and in light of the imperative that experts be independent the Tribunal considers that there is prima facie evidence of impermissible interference by HMRC through the auspices of the solicitor in the finalisation of the joint statement.  At the very least there is a perception of such interference.  Mr Orrock’s instructing client/solicitor apparently appreciated the significance of the concession implicit in the language originally proposed by Mr Brice and largely accepted by Mr Orrock (at least by reference to his limited changes to that draft prior to the involvement of the solicitor). 

[84] The perception given of the interactions given by reference to the material available, does, in the Tribunal’s view, give very real cause for concern that there is an impropriety." (Wired Orthodontics Limited v. HMRC [2020] UKFTT 290 (TC), Judge Amanda Brown)

Joint reports

Court should focus on substance rather than manner of presentation


"[21]...Otherwise I do not accept the criticisms made, whilst accepting that Dr Tonks did come across as an experienced and persuasive expert and reminding myself that a judge must be astute to consider the substance of the evidence rather than the manner of its presentation. Having heard his evidence and having re-read the transcript of his evidence I am quite satisfied that he did not cross the line into inappropriate advocacy or partisan evidence." (BDW Trading Ltd v. Integral Geotechnique (Wales) Ltd [2018] EWHC 1915 (TCC))

Court should focus on substance rather than manner of presentation



- Risk to independence from need to maintain a source of instructions and pressure to prepare favourable report


"[287] Some care experts have a (full time) private practice solely preparing reports for either Claimants or Defendants. Given that the compilation of a care report often requires a significant amount of subjective judgment, there is an obvious risk of contravention of Cresswell J’s first principle and CPR 35.3. (2) through a lack of true independence arising from the need to maintain a source of instructions and the pressure to prepare a report which is favourable to the instructing party.

[288] There is also often, if not usually, a very marked aversion shown by those conducting higher value personal injury or clinical negligence claims to the use of single joint care experts, despite the fact that there is often no principled reason against such an instruction.   In my view the common working assumption within these fields of litigation that it is axiomatically the case that each party will have a care expert is misplaced, helps perpetuate polarised expert opinions and often greatly increases the cost of litigation.


[304] After I asked (her report contained no breakdown [34]) Ms Kerby revealed that she has been preparing reports solely on behalf of Claimants for nine years. She recognised the understandable concern a Court will have as to the risks that arise when an expert’s workload (and income) is solely for one side to litigation. In my view the risk came to fruition and the reports she prepared contained some partisan views designed to maximise damages for the Claimant rather than recommendations made, as they should have been, after balanced and objective application of the relevant principles." (Muyepa v. Ministry of Defence [2022] EWHC 2648 (KB), Cotter J)

- Risk to independence from need to maintain a source of instructions and pressure to prepare favourable report

- HMRC's approach of appointing employed experts and potential impropriety

"[The taxpayer] invites the Tribunal to find that Mrs Reeves, while honest, was unconsciously unable to maintain her independence due to the fact that she is employed for the last 14 years by HMRC and as such all her training, professional development and experience has been gained in the context of HMRC’s control (and considering her professional opinion has accorded with HMRC’s view of the accounting treatment). I am not persuaded by Ms Brown’s submission. I do not consider Mrs Reeves’ HMRC employment alone to be a sufficient basis to challenge her professional integrity and independence. I consider Mrs Reeves to have given credible evidence of her mindful independence, saying that: “I consider whether I am able to give an honest and free from bias opinion, and I believe that I am. I’m under no pressure to give any particular opinion.” It is my finding that Mrs Reeves understood her duty to the Tribunal and gave her opinion uninfluenced by partisan considerations (see Anglian Water Services Ltd v HMRC [2017] UKFTT 386 (TC) at [83])." (Northwood v. HMRC [2023] UKFTT 351 (TC), Judge Sukul)

"[118] The circumstances giving rise to this application are cause for considerable concern to the Tribunal.

[119] Mr Tolley QC made the observation during the hearing that HMRC are in an invidious position when expert accounting evidence is required to determine complex tax appeals.  They cannot simply appoint expert accountants employed in practice because of the apparent or actual conflict of interest which may arise between the firm employing the accountant and their clients and the receipt of instructions from HMRC.

[120] The Tribunal has historically accepted this difficulty as reason to accept that HMRC will therefore appoint experts employed by HMRC.  It is essentially considered to be the lesser of two evils.

[121] However, in the circumstances, but placing no greater onus on such experts or those instructing them, it is absolutely imperative that the independence of the expert is preserved, and that independence is seen to be preserved.

[122] By reference to the material seen by the Tribunal, and as articulated in the substance of this judgment, there is evidence of, at the very least, potential inappropriate interference with the independent evidence of an expert witness.  It may be the case that were the instructions to be reviewed that it would transpire that there was, in fact, no actual inappropriate interference but the perception given is that there was a transgression.  In the terms articulated in BDW a serious transgression.

[123] Such a perception is seriously prejudicial to HMRC’s position in cases such as these and should be avoided at all costs." (Wired Orthodontics Limited v. HMRC [2020] UKFTT 290 (TC), Judge Amanda Brown)

- HMRC's approach of appointing employed experts and potential impropriety

- Partisan views/favourable factual assumptions on one area calls into question all views taken


"[316] Mr Craggs gave the opinion that the Claimant could have been retained as a driver within the army despite an NFCI but that as he would have to be out in all weathers and service the vehicle this may have been impractical. He also accepted there were many soldiers with a logistics role deployed in the field, but he did not see that it was likely that the Claimant would have been retained in such a role. However, the difficulty with expressing partisan views (and making factual assumptions/findings favourable to an instructing party) when giving an expert opinion is that it calls into question the reliability of views expressed elsewhere. Put simply if the aim is to assist the Claimant to advance his case any answer has to be viewed with caution." (Muyepa v. Ministry of Defence [2022] EWHC 2648 (KB), Cotter J)

"[90] I agree with HMRC that an expert should provide a balanced analysis and not simply present matters which provide support for their conclusion. Mr Powrie did not refer to the lack of security or credit checks in his analysis of the loans, although he did mention that he understands “that it may be that the trustees will then roll these loans over or, in other ways, provide compensation if Mr Northwood has to repay the loans” before he concluded that “it does not seem to me to be right to say that monies which have, through a variety of processes, ended up as loans to the proprietor of a business on interest bearing terms and subject to repayment can be drawings”.

[91] In general terms, as HMRC submits, Mr Powrie’s analysis focused on arguing against HMRC contentions. Mr Powrie states in his report that he understands that he should not assume the role of an advocate. However, he refers to “various statements of accounting practice which may be relevant to our structure” and then states that the “question then arises as to how the purported contributions should be treated for accounting purposes within that framework. It appears to me that there are four separate contentions made by HMRC as to how they should be treated and each of them raise different issues”, before setting out his opinion, rejecting HMRC’s contentions. Such an approach does give support to HMRC’s argument that Mr Powrie assumed the role of an advocate. However, I have also considered that, whilst Mr Powrie’s conclusions rely upon the acceptance of Mr Northwood’s evidence, he also makes references to alternative findings of fact or law being matters for determination by the Tribunal that would lead him to different conclusions. I therefore do not consider Mr Powrie’s actions go as far as amounting to neglect of his duties as an independent expert. I do, however, consider the approach taken by Mr Powrie to affect the weight I give to his evidence and I have no hesitation in preferring Mrs Reeves’ balanced analysis and report, supported by detailed references to accountancy standards and materials." (Northwood v. HMRC [2023] UKFTT 351 (TC), Judge Sukul)

- Partisan views/favourable factual assumptions on one area calls into question all views taken
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