Do experts have to disclose the reasons for their opinions?

The simple answer is ‘No’.  But read on…

In the recent case of Griffiths v Tui [2008] EWHC 2268 the judge held that there is a threshold which an expert report must pass for it to be accepted as evidence in a case.  And what is that threshold?  It is to comply with the requirements of the Practice Direction to Part 35 of the Civil Procedure Rules

The contents of the Practice Direction will be well known to all experts working in the Civil Courts, and equivalent Rules will be familiar to experts in other courts.  While there is a requirement that the report is addressed to the court, that the report gives details of the expert’s qualifications, that it sets out the substance of all facts and instructions which are material to the opinions expressed or on which the opinions are based, and so on, nowhere is there a requirement for the expert to give reasons for any opinion contained in the report.  Indeed the statement of truth at para 3.3, while requiring confirmation of which facts and matters are within the expert’s own knowledge and which are not, and confirmation that the former are true, and confirmation that the opinions expressed are the expert’s true and complete professional opinions on the matters to which they refer, makes no reference to the expert’s reasoning.

It follows that an expert’s report is complete and admissible in evidence without giving any reasons for the opinions expressed as long as it complies with the requirements in the Practice Direction. 

This is at first sight completely contrary to everything that Medico-Legal Minder goes on about when training expert witnesses – identify the material facts, provide  the reasoning and state the opinion that flows from those facts and the reasoning process, because an opinion in the absence of showing the reasoning which takes one to it is without value.

In Griffiths the only expert evidence available to the trial judge was that in the claimant’s written expert report and the written answers to questions under Part 35.  There was no oral evidence from the expert, no cross-examination, and no contrary expert evidence.  The judge hearing the trial found that there were gaps in the reasoning in the report and that the report contained opinions which were what some lawyers still insist on calling ‘bare ipse dixit’, or what anyone else would call mere assertions without proof.

The judge hearing the appeal from that finding held that, while there were serious deficiencies in the report which could have caused the expert serious embarrassment had the report been challenged, it did not contain mere assertions without proof, even if the report was lacking in showing the expert’s reasoning process resulting in the opinions expressed.  The report substantially complied with the Practice Direction, which meant that it could not be characterised as a mere assertion without proof, and as it was not challenged by the defendant the judge was bound to accept it.

This case illustrates well the difference between what the Civil Procedure Rules require and what a good report must contain.  An expert, and the party on whose behalf they are instructed, can get away without providing reasoning, or adequate reasoning, in the report if the report is not challenged.  But if that report is challenged, that is most likely to be inadequate, and the expert’s evidence unsupported by reasoning provided in the report is likely to be rejected.

But why would a respectable and competent expert provide a report with an opinion without explaining to the reader of the report how the expert came to that opinion?  Only then can the reader assess the strength of that opinion, at least by way of logical analysis even if the reader lacks the required expertise to assess it as an expert of similar expertise, and compare, and weigh, that opinion against any other opinion provided by another expert on the same issue.

When providing an expert report, you must identify the material facts, and then provide the reasoning which takes the expert to the opinion.  As the maths teacher said ‘show your working’.

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Stating the ‘bleeding obvious’

It is hard to believe that any court expert signing a statement of truth, in accordance with para 3.3 of the Practice Direction to Part 35 of the Civil Procedure Rules, at the end of their expert report verifying its accuracy, has any real doubt that were the statement found to be false then the expert would be open to proceedings for contempt, and that would put the expert in jeopardy of imprisonment – see for example Liverpool Victoria Insurance v Zafar [2019] EWCA Civ 392.

However, to ensure that the fear of prison runs through every expert as they sign off on a report, the Practice Direction is to be amended as of 1st October 2020 to add, at the end of the existing statement of truth:

“I confirm that I have made clear which facts and matters referred to in this report are within my own knowledge and which are not. Those that are within my own knowledge I confirm to be true. The opinions I have expressed represent my true and complete professional opinions on the matters to which they refer.”

the following sentence:

“I understand that proceedings for contempt of court may be brought against anyone who makes, or causes to be made, a false statement in a document verified by a statement of truth without an honest belief in its truth.”

Every expert report from 1st October 2020 must have this additional sentence at the end of the statement of truth, to remind the expert that the ‘starting point’ for someone found guilty of contempt is a sentence of imprisonment ‘well in excess of 12 months’, according to Zafar – see my earlier blog Your statement of truth really, really matters!.

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