[60] In his discussion of the point Floyd LJ quoted the obligation to cross-examine set out in the 19th edition of Phipson (2018) and referred to Browne v Dunn and Markem . Floyd LJ recognised that the rule is an important one, but, like the Board in Chen v Ng (which appears not to have been cited to the Court of Appeal), he did not consider it to be an inflexible one. In his discussion in paras 63-69 he made six points. First, where, to save time, it is proposed not to cross-examine two witnesses on the same or similar subject matter it was good practice to raise the matter with the judge and obtain his or her directions to ensure fairness. (That suggestion is not relevant to this appeal). Secondly, the purpose of the rule is not only for the benefit of the witness but is to ensure the overall fairness of the proceedings for the parties. Thirdly, the rule applies with particular force where a witness gives evidence of fact of which the witness has knowledge, and it is proposed to invite the court to disbelieve that evidence. Fairness to the witness and to the parties demands that the witness be given the opportunity to respond to the challenge. Fourthly, it was not appropriate to apply the rule rigidly in every situation. Where, as in the case in question, there had been an opportunity to respond to the other side’s case through several rounds of expert evidence which made the position taken by each side’s experts clear, the potential for unfairness to the witness was much reduced. Fifthly, not every part of the evidence of a witness to fact needs to be challenged head-on that it is untrue or simply misguided; the test was fairness; see Various Claimants v Giambrone & Law [2015] EWHC 1946, para 21 per Foskett J . Sixthly, the question for the appellate court is “whether the decision not to cross-examine has led to unfairness to the extent that the judge’s decision on the relevant issue is thereby undermined” (para 69). In that case, there had been no unfairness to the expert witness or the party adducing his evidence as the witness had had the opportunity to respond to the case made against his position.
[61] From this review of the case law it is clear that there is a long-established rule as stated in Phipson at para 12.12 with which practising barristers would be familiar, as Bean LJ suggested in para 87 of his judgment. There are also circumstances in which the rule may not apply. Several come to mind. First, the matter to which the challenge is directed is collateral or insignificant and fairness to the witness does not require there to be an opportunity to answer or explain. A challenge to a collateral issue will not result in unfairness to a party or interfere with the judge’s role in the just resolution of a case; and a witness in such a circumstance needs no opportunity to respond if the challenge is not an attack on the witness’s character or competence.
[62] Secondly, the evidence of fact may be manifestly incredible, and an opportunity to explain on cross-examination would make no difference. For example, there may be no need for a trial and cross-examination of a witness in a bankruptcy application where the contemporaneous documents properly understood render the evidence asserted in the affidavits simply incredible: Long v Farrer & Co [2004] EWHC 1774 (Ch); [2004] BPIR 1218, para 60, in which Rimer J quotes from the judgment of Chadwick J in In re Company (No 006685 of 1996) [1997] 1 BCLC 639, 648.
[63] Thirdly, there may be a bold assertion of opinion in an expert’s report without any reasoning to support it, what the Lord President (Cooper) in Davie v Magistrates of Edinburgh described as a bare ipse dixit. But reasoning which appears inadequate and is open to criticism for that reason is not the same as a bare ipse dixit.
[64] Fourthly, there may be an obvious mistake on the face of an expert report. Bean LJ referred to this possibility in para 94 of his judgment and cited Woolley v Essex County Council [2006] EWCA Civ 753 as a useful example. In Hull v Thompson [2001] NSWCA 359, (“ Hull v Thompson ”) Rolfe AJA at para 21 expressed the view that such a circumstance would be where the report was ex facie illogical or inherently inconsistent. See also A/S Tallinna Laevauhisus v Estonian State Steamship Line (1946) 80 Ll L Rep 99, 108 (“ Tallinna ”) where Scott LJ spoke of the court rejecting an expert’s evidence if “he says something patently absurd, or something inconsistent with the rest of his evidence.”
[65] I would add that what is said about the evaluation of expert evidence of foreign law in Tallinna and the other cases cited by the parties in argument in this appeal may now need to be read in the light of the recent guidance of this court in Brownlie v FS Cairo (Nile Plaza) LLC [2021] UKSC 45, [2022] AC 995 and of the Board in Perry v Lopag Trust Reg [2023] UKPC 16; [2023] 1 WLR 3494.
[66] Fifthly, the witnesses’ evidence of the facts may be contrary to the basis on which the expert expressed his or her view in the expert report. Rolfe AJA in Hull v Thompson , para 21, spoke of the report being “based on an incorrect or incomplete history, or where the assumptions on which it is founded are not established.”
[67] Sixthly, as occurred in Edwards Lifesciences , an expert has been given a sufficient opportunity to respond to criticism of, or otherwise clarify his or her report. For example, if an expert faces focused questions in the written CPR Pt 35.6 questions of the opposing party and fails to answer them satisfactorily, a court may conclude that the expert has been given a sufficient opportunity to explain the report which negates the need for further challenge on cross-examination.
[68] Seventhly, a failure to comply with the requirements of CPR PD 35 may be a further exception, but a party seeking to rely on such a failure would be wise to seek the directions of the trial judge before doing so, as much will depend upon the seriousness of the failure.
[69] Because the rule is a flexible one, there will also be circumstances where in the course of a cross-examination counsel omits to put a relevant matter to a witness and that does not prevent him or her from leading evidence on that matter from a witness thereafter. In some cases, the only fair response by the court faced with such a circumstance would be to allow the recall of the witness to address the matter. In other cases, it may be sufficient for the judge when considering what weight to attach to the evidence of the latter witness to bear in mind that the former witness had not been given the opportunity to comment on that evidence. The failure to cross-examine on a matter in such circumstances does not put the trial judge “into a straitjacket, dictating what evidence must be accepted and what must be rejected”: MBR Acres Ltd v McGivern [2022] EWHC 2072 (QB), para 90 per Nicklin J. This is not because the rule does not apply to a trial judge when making findings of fact, but because, as a rule of fairness, it is not an inflexible one and a more nuanced judgment is called for. In any event, those circumstances, involving the substantive cross-examination of the witness, are far removed from the circumstances of a case such as this in which the opposing party did not require the witness to attend for cross-examination.
[70] In conclusion, the status and application of the rule in Browne v Dunn and the other cases which I have discussed can be summarised in the following propositions:
(i) The general rule in civil cases, as stated in Phipson, 20th ed, para 12-12, is that a party is required to challenge by cross-examination the evidence of any witness of the opposing party on a material point which he or she wishes to submit to the court should not be accepted. That rule extends to both witnesses as to fact and expert witnesses.
(ii) In an adversarial system of justice, the purpose of the rule is to make sure that the trial is fair.
(iii) The rationale of the rule, ie preserving the fairness of the trial, includes fairness to the party who has adduced the evidence of the impugned witness.
(iv) Maintaining the fairness of the trial includes fairness to the witness whose evidence is being impugned, whether on the basis of dishonesty, inaccuracy or other inadequacy. An expert witness, in particular, may have a strong professional interest in maintaining his or her reputation from a challenge of inaccuracy or inadequacy as well as from a challenge to the expert’s honesty.
(v) Maintaining such fairness also includes enabling the judge to make a proper assessment of all the evidence to achieve justice in the cause. The rule is directed to the integrity of the court process itself.
(vi) Cross-examination gives the witness the opportunity to explain or clarify his or her evidence. That opportunity is particularly important when the opposing party intends to accuse the witness of dishonesty, but there is no principled basis for confining the rule to cases of dishonesty.
(vii) The rule should not be applied rigidly. It is not an inflexible rule and there is bound to be some relaxation of the rule, as the current edition of Phipson recognises in para 12.12 in sub-paragraphs which follow those which I have quoted in para 42 above. Its application depends upon the circumstances of the case as the criterion is the overall fairness of the trial. Thus, where it would be disproportionate to cross-examine at length or where, as in Chen v Ng , the trial judge has set a limit on the time for cross-examination, those circumstances would be relevant considerations in the court’s decision on the application of the rule.
(viii) There are also circumstances in which the rule may not apply: see paras 61-68 above for examples of such circumstances.
