Expert Evidence and Burden of Proof – The Case of Griffiths v Tui (UK)


Expert Evidence and Burden of Proof in UK Law

“People are tired of experts” is a well-known expression uttered by a prominent politician. This expression is not – however – to be followed in civil / public / family law litigation, and those that do follow it do so at their own peril. 


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In UK law, expert evidence and burden of proof can work together to make or break a case. 
This is because Courts often need non-partisan evidence to assist them in assessing a contentious point that cannot be taken from the witness evidence of the parties, not in the least since the burden of proof always rests with the Plaintiff in civil proceedings – this point was eloquently summarised by HHJ Paul Matthews in the case of Ball & Ors v Ball & Ors [2017] EWHC 1750 (Ch) (at [19]) where it was observed that:


“…it is for the parties to find and put before the Court the material which they think will best help the Court and prove their case. The English courts do not investigate on their own motion. It may often be that other relevant material exists elsewhere. But the Court does not go and look for it. In civil litigation, the Court usually makes its decision only on the basis of the material put before it by the parties.”


Of course, the need to have Independent Expert Evidence may and often will – precede litigation, particularly where a party needs to make its case to a public authority decision-maker. This will mean instructing experts across the range of subject matters, which can include Independent Social Workers, Independent Psychologists, Independent Psychiatrists, Independent Country Experts, Independent Forensic Accountants, Independent Expert Valuers, Independent Medical Specialists and so on. 


Matters of Expert Evidence and Burden of Proof have been featured in reported cases to a large degree across recent years. The cases of Bux v The General Medical Council [2021] EWHC 762 and Leach v North East Ambulance Service NHS Foundation Trust [2020] EWHC 2914 (QB)  addressed the issues of lack of objectivity and conflict of interest displayed by experts appearing in these cases, with a similar issue having been addressed in the recent judgment in  


CSB 123 Ltd, Re [2021] EWHC 2506 (Ch)

Largely, however, the recent case relating to Expert Evidence has been that of the High Court. This, therefore, could be said to have prompted the Court of Appeal to deliver one of its most important judgments dealing with matters of expert evidence in Griffiths v Tui (UK) Ltd [2021] EWCA Civ 1442

Expert Evidence and Burden of Proof – The Case of 
Griffiths v Tui (UK) 

 was – notably – not a unanimous judgment, but a 2-1 majority judgment, with Bean LJ providing a dissenting opinion. The Court of Appeal held that judges are not required to accept ‘uncontroverted’ – i.e., unchallenged – evidence from an expert witness without further analysis. 


Griffiths was a holiday sickness claim, where the Plaintiff sued over food poisoning and subsequent gastric illness, which he says he suffered while on holiday in Turkey. The Defendant tour operator’s (TUI’s) case was that the evidence was merely deficient. 

At trial before Her Honour Judge Truman (at the County Court) – which would have been a Multi Track claim given the complexity – the Plaintiff relied on a medical report – which the Defendant did not challenge by way of evidence or cross-examination – where the findings in that report were then challenged by the Defendant in the Defendant’s closing submissions. The claim was dismissed in the first instance by HHJ Truman due to the expert’s failure to fully consider all potential causes of illness.


The Plaintiff appealed to the High Court stating that, where an expert report is in its genuine form, it should not be denied by the Court, unless there is an exceptional situation. In the High Court, Martin Spencer J agreed to this and allowed the appeal to proceed, stating: “Once a report is truly uncontroverted, that role of the court falls away.” This was as long as the report complied with Part 35 of the Civil Procedure Rules (CPR Part 35) and was more in depth than just a bare assertion of opinion – a relatively low bar. 


The Defendant (TUI) appealed to the Court of Appeal. The Court of Appeal allowed the appeal by majority. Lady Justice Asplin enforced that challenging expert evidence in closing submissions is “a high-risk strategy”, but a stratgey someone can follow where it was not challenging the veracity of an expert’s evidence. In her view, the Defendant was allowed to submit that “an essential aspect of the case has not been proved to the requisite standard”; nor need it provides an opportunity for the other party to resolve the deficiencies in its evidence. 


Giving the lead judgment, Asplin LJ said: “The authorities do not support the bright-line approach adopted by the judge. There is no rule that an expert’s report which is uncontroverted and which complies with CPR PD 35 cannot be impugned in submissions and ultimately rejected by the judge.” 


The trial judge (HHJ Truman) had been correct to reject the expert evidence due to its inadequacies. Most importantly, this was not because the expert’s evidence was not believed, in which case it should be challenged in cross-examination, Asplin LJ said. Further, Asplin LJ held that the strict test applied by Martin Spencer J was not correct because it was not the role of a trial judge to rubber-stamp expert evidence. Asplin LJ also stated: “If it were otherwise, the court would be bound by an uncontroverted expert’s report… even if the conclusion was only supported by nonsense.” 


In a concurring opinion, Lord Justice Nugee stated: “As a matter of basic principle, it is the function of trial judges to evaluate all the evidence before them in reaching their conclusions on the factual issues. That includes deciding what weight should be given to the evidence.” 


Lord Justice Bean provided a dissenting opinion to those of Asplin and Nugee LJJ. Bean LJ saying that the rule that a witness must be scrutinized by cross-examination if they were alleged to be lying was “wider than that” and relevant to both lay witnesses and experts. 

“It does not extend to every point of detail in a long witness statement: that is a matter for the discretion and common sense of the trial judge. 


But in this case, a clear conclusion was given by the expert on the very issue of which he was asked to give an opinion on, specifically that ‘on the balance of probabilities Peter Griffiths acquired his gastric illnesses after consuming contaminated food or fluid from the hotel’. These points could and should have been challenged in cross-examination.” 


Bean LJ said a judge was “generally bound” to accept the evidence of an expert if such is not denied by other expert, factual, or relevant evidence, and the opposition “could have cross-examined the expert on the point but chose for tactical reasons not to do so”. 

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So, where does that leave us, and what’s the takeaway? 

Well, so far, this is the most up-to-date and highest case-law authority on expert witness evidence. Until such time that the UK Supreme Court (UKSC) says otherwise – it is unknown whether a) an application to the UKSC directly for permission to appeal is being pursued (since the Court of Appeal refused permission to appeal) will be granted by the UKSC itself and b) even if the UKSC decides to hear it, we don’t know what the law may be going forward – this is what we have.  


Some may be inclined to think that this judgment has “thrown the cat amongst the pigeons”. I would, however, respectfully disagree.  


Rather, I would say that this judgment only goes to highlight the needs of modern plaintiffs and litigators to: 


  1. Properly vet the expert witnesses before they come on board, including as to their methodology. Experts cannot and should not “shoot from the hip”especially when it comes to causation, as was seen in both Jones v Ministry of Defence [2020] EWHC 1603 (QB) and Griffiths, since this can fatally damage a case.
  2. Ensure that the expert witnesses have comprehensive written instructions and materials to hand to enable them to provide detailed, articulated conclusions
  3. Have as much expert evidence as possible right from the outset without trying to “wing it” in the hopes that a single expert report may suffice. Scientific methodology would suggest that you need at least 2-3 experts in each subject area to provide detailed testimony to demonstrate that any assertions/arguments are not barefaced/threadbare statements devoid of substance. The need to have multiple experts to address complex cases was visited upon by the Court in Borro Ltd & Ors v Aitken [2021] EWHC 1902 (Ch), with the Court remarking that “an order directing one expert would run the risk of tempting an expert outside his or her area of expertise”.
  4. Thoroughly vet and test the Plaintiff’s / Appellant’s evidence to ascertain whether it’s congruent with any objective evidence, including Independent Expert Evidence. There is nothing more professionally demeaning than having the Plaintiff give testimony that flies in the face of the objective evidence, undoing hard work that preceded such a fiasco.
  5. Ensure that you budget ahead with a comfortable margin. Competent Independent Expert Witnesses do not come cheap – their charges do ordinarily start at around £ 3500 – 4500 mark per written report and venture upwards depending on the complexity of the case. With the advent of modern-day crowdfunding/fundraising platforms such as GoFundMe and CrowdJustice, there is simply no reason why individuals can’t make use of them to source the necessary funds to build their case properly. Good preparation and solid funding are a key investment in a complex and contentious case since a well-built and comprehensive case is far more likely to succeed, at the risk of sounding awfully obvious. 

As noted by the Court of Appeal in 
Griffiths, it is not the function of a trial judge to rubber-stamp expert evidence. It can be said that this is a principle that applies across various subject areas in law, be it Family Law, Immigration Law, Planning Law or general Civil Litigation. Essentially, what Griffiths imparts on us all is that Expert Evidence needs to be cogent and properly backed AND support any arguments being made on behalf of any given party. 


Article written by:

Mr. Hayk K Sayadyan Esq.

Senior Consultant Solicitor

Gulbenkian Andonian Solicitors 

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