Most expert reports in road traffic claims are competent on the engineering and careless on the rules. That carelessness costs the party who paid for the report, because a judge who cannot see the rules being followed will give the opinion less weight, and an opponent who can see them being broken will say so in cross-examination. Part 35 is short. It is worth knowing what it actually says.
The starting point: is expert evidence needed at all?
Rule 35.1 restricts expert evidence to what is reasonably required to resolve the proceedings, and rule 35.4 means no party may call an expert or put in a report without the court’s permission. In the small claims and fast tracks that permission is tightly controlled. The first job of an engineer asked to help is therefore to say whether the question is one the court needs an expert for, and in what form. A short screening opinion that tells a solicitor “this does not need a Part 35 report” is doing its job properly.
The duty
Rule 35.3 states the duty in two sentences: the expert’s duty is to help the court on matters within their expertise, and that duty overrides any obligation to the person from whom the expert has received instructions or by whom they are paid. Everything else in Part 35 is machinery for making that duty visible.
The content of the duty was set out before the Civil Procedure Rules existed, by Cresswell J in The Ikarian Reefer. Expert evidence should be, and be seen to be, the independent product of the expert, uninfluenced in form or content by the exigencies of litigation. The expert should provide independent assistance by way of objective, unbiased opinion, and never assume the role of an advocate. The facts or assumptions on which the opinion is based should be stated, together with material facts which could detract from the concluded opinion. The expert should make it clear when a question falls outside their expertise, and when an opinion is provisional because insufficient data were available. If, after exchange of reports, the expert changes their view, that should be communicated to the other side without delay. Those principles are now reflected in Practice Direction 35 and in the Civil Justice Council’s Guidance, but reading the original is still the quickest way to understand what a court is looking for.
What the report must contain
Paragraph 3.2 of the Practice Direction lists the required contents. In summary, a report must:
- give details of the expert’s qualifications;
- give details of any literature or other material relied on;
- contain a statement setting out the substance of all facts and instructions which are material to the opinions expressed or on which they are based;
- make clear which of the facts stated are within the expert’s own knowledge;
- say who carried out any examination, measurement, test or experiment used for the report, give their qualifications, and say whether it was carried out under the expert’s supervision;
- where there is a range of opinion on the matters dealt with, summarise the range and give reasons for the expert’s own opinion;
- contain a summary of the conclusions reached;
- if the expert is not able to give an opinion without qualification, state the qualification; and
- contain a statement that the expert understands their duty to the court, has complied with it, and is aware of the requirements of Part 35, the Practice Direction and the Guidance.
Two of these are where engineering reports most often fall short. Item 3 is not satisfied by “I was instructed by X to consider liability”. It requires the substance of the instructions, and rule 35.10(4) makes those instructions potentially open to inspection if the statement is thought inaccurate or incomplete. Item 6 is not satisfied by silence. If analysis methods differ, or published friction values span a range, the report has to say so and explain why the expert lands where they do.
The statement of truth
Paragraph 3.3 prescribes the wording, and it should appear verbatim:
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.
An expert who signs that statement knowing it to be false may face proceedings for contempt. Since Jones v Kaney, an expert who is negligent in preparing a report or giving evidence may also be sued by the party who instructed them. Immunity from suit no longer applies.
Written questions and the single joint expert
Rule 35.6 allows a party to put written questions to an expert within 28 days of service of the report, once, for the purpose of clarification. The answers become part of the report. A report written clearly in the first place attracts fewer questions, and answers that are evasive do real damage. Where the court directs a single joint expert under rule 35.7, both parties may give instructions, and the expert owes the same duty to each. The method, the sources and the opinion do not change with the identity of the instructing party, and a single joint expert report is the clearest test of whether that is true.
Admissibility and weight
The Supreme Court in Kennedy v Cordia, a Scottish appeal whose reasoning has been applied in England and Wales, set out four considerations for expert evidence: whether it will assist the court, whether the witness has the necessary knowledge and experience, whether the witness is impartial, and whether there is a reliable body of knowledge or experience to underpin the evidence. A collision analysis report that cites its sources, states its tolerances and shows its calculations answers the fourth of those questions on its face. One that asserts a speed to the nearest mile per hour without saying how does not.
In practice
The rules are not a formality to be satisfied by a template at the back of the report. They describe what a useful, honest piece of expert evidence looks like. A report that sets out the papers it was given, says what is missing, states its assumptions, cites its data, gives the range and explains the choice within it, and declares its limitations, is both compliant and persuasive. Those turn out to be the same thing.