Part 35 questions are written questions that a party puts to an expert about their report, under rule 35.6 of the Civil Procedure Rules. They can go to an expert instructed by another party or to a single joint expert, once, within 28 days of service of the report, and only to clarify it unless the court gives permission or the other party agrees. The expert's answers are treated as part of the report. This guide covers the rules, where the line on clarification falls, who pays, and how solicitors should draft the questions and experts should answer them.

The practical bottom line

  • Who can be asked. Another party's expert or a single joint expert (CPR 35.6(1)). The rule does not cover your own expert.
  • When. Once only, within 28 days of service of the report (CPR 35.6(2)).
  • What for. Clarification of the report, unless the court gives permission or the other party agrees to wider questions. Every set must be proportionate.
  • What the answers are. Part of the expert's report (CPR 35.6(3)), which any party may use at trial once it is disclosed (CPR 35.11).
  • Who pays. The party who instructed the expert, subject to the court's later decision on costs (Practice Direction 35, para 6.2).
  • If there is no answer. The court can stop the instructing party relying on the expert, or recovering the expert's fees from any other party (CPR 35.6(4)).

What are Part 35 questions?

An expert's report is written once and read many times, often by people who had no part in the instruction. Part 35 questions give the other side a cheap, written way to find out what a report means before the experts meet or anyone goes into the witness box. Rule 35.6 says a party "may put written questions about an expert's report (which must be proportionate)" to "an expert instructed by another party" or to "a single joint expert appointed under rule 35.7".

The answers "shall be treated as part of the expert's report" (CPR 35.6(3)). The Civil Justice Council's guidance for the instruction of experts adds that they are covered by the statement of truth and form part of the expert evidence (para 68). That status matters to the party who instructed the expert, because under CPR 35.11 any party may use a disclosed report as evidence at trial. A concession made in answer to a well-aimed question belongs to the case from then on, whoever paid for the report.

The rule does not apply to your own expert. Points for your own expert go through your instructions, and if the expert's view changes as a result, Practice Direction 35 requires the change to be communicated to all the parties without delay (para 2.5). For the rest of Part 35, see our guide to CPR 35.

What are the rules for Part 35 questions?

Rule 35.6 and paragraph 6 of Practice Direction 35 set five conditions:

  1. Once only. One set of questions per report (CPR 35.6(2)(a)).
  2. Within 28 days of service. The period runs from service of the report (CPR 35.6(2)(b)). Directions orders can set their own dates for questions and answers, so read the order first.
  3. For clarification only. Questions must be "for the purpose only of clarification of the report" (CPR 35.6(2)(c)).
  4. Proportionate. The set as a whole must be proportionate (CPR 35.6(1)).
  5. Copied to everyone. A party who sends questions direct to the expert must send a copy to the other parties at the same time (PD35 para 6.1).

The first three conditions give way if the court gives permission or the other party agrees (CPR 35.6(2)). A late set, a second set or a set that goes beyond clarification is therefore possible, but it needs that agreement or an order. Asking the other side first is cheaper than an application, and any agreement should be recorded in writing. The proportionality requirement has no such exception.

What counts as clarification?

The rules do not define clarification, and where the line falls depends on the report and the issues. A workable test is whether the question asks the expert to explain what the report already says, or asks for something the report does not contain. Some illustrations from a clinical negligence report:

Usually clarification:

  • "At paragraph 5.4 you refer to a delay in referral. What period of delay do you mean, and from which date do you measure it?"
  • "Which entries in the GP records support the statement at paragraph 6.2 that the symptoms were first reported in March 2023? Please give page references."
  • "Please identify the literature referred to at paragraph 7.3." Practice Direction 35 requires a report to give details of the literature relied on (para 3.2(2)).

Usually beyond clarification:

  • Asking the expert to comment on new material, such as another expert's report or records disclosed after the report was written.
  • Asking for an opinion on an issue the report does not address, or one outside the expert's instructions.
  • Asking the expert to carry out a new examination, test or literature review.
  • Leading or argumentative questions that put the asking party's case and invite agreement, which is cross-examination in writing.

Questions in the second group are not always improper. In Mutch v Allen [2001] EWCA Civ 76 the Court of Appeal allowed a question to the claimant's expert that went beyond simple clarification. What the rule requires is that a question of that kind comes with the other party's agreement or the court's permission.

When are Part 35 questions disproportionate?

The proportionality requirement was added to the rule later, to deal with lengthy, complex sets of questions that were, in reality, a form of cross-examination. That is how Master Davison described its purpose in Mustard v Flower [2019] EWHC 2623 (QB), the clearest recent example of a set of questions that crossed the line.

The claim followed a rear-end collision, and the experts disagreed sharply over whether the claimant had suffered a significant brain injury. The claimant's questions to the defendant's experts, with their appendices, filled two ring binders. Six of the defendant's experts wrote to the court asking for directions, some saying the answers would take two or three working days. The Master accepted that the questions were relevant and that some addressed accepted omissions in the reports, but disallowed them because they were wholly disproportionate, were overwhelmingly not for the purposes of clarification and amounted to cross-examination. The omissions, he held, were best addressed by supplementary reports and by the experts' joint meetings and statements.

The judgment also shows how rarely experts go to the court over questions. The Master recorded that the longest-serving Master had received letters of that kind from experts just twice in 18 years.

How should a solicitor draft Part 35 questions?

  • Diarise the deadline on service. The 28 days run from service of the report, and the order may set a different date.
  • Decide whether to ask at all. Questions show the other side where you think the report is weak, and an expert pressed on a point in writing may simply restate it more firmly. Ask where the answer will narrow an issue or pin down a point you need.
  • Tie every question to the report. Cite the paragraph and page, so the expert and the court can see what is being clarified.
  • One point per question, numbered. Compound questions get compound answers.
  • Use neutral wording. A question that argues your case invites an objection and reads as cross-examination.
  • Keep the set proportionate. A handful of targeted questions on the issues that decide the case usually achieves more than a long list.
  • Copy every other party at the same time if you send the questions direct to the expert (PD35 para 6.1).
  • Get agreement first for anything late, repeated or wider than clarification, and apply to the court if it is refused.
  • With a single joint expert, put written questions before asking for the expert to attend court for cross-examination, as the CJC guidance recommends (para 47).

How should an expert answer Part 35 questions?

The CJC guidance is direct: "Experts have a duty to provide answers to questions properly put" (para 67). A sound set of answers:

  • repeats each question with its number and answers directly beneath it;
  • points back to the paragraph of the report and the page of the records each answer rests on;
  • stays inside the expert's field, and says so when a question falls outside it, as paragraph 2.4 of Practice Direction 35 requires;
  • says where the records needed to answer were not provided (see what to do when the disclosure has gaps);
  • says plainly when an answer changes the opinion, because a change of view on a material matter must reach all the parties without delay (PD35 para 2.5), and a significant change means amending the report and explaining why (CJC para 66);
  • is signed, dated and copied to those instructing (CJC para 67), since the answers carry the report's statement of truth.

Write the answers for the judge. The questions come from the other side, but the duty in CPR 35.3 runs to the court, and conceding a fair point is part of that duty. An expert who defends every sentence against a reasonable question starts to look partisan, which costs more at trial than the concession would have.

A good Part 35 question can be answered from the report and the records already in the bundle. If answering it needs new work, it is probably asking for more than clarification.

Because the answers carry the report's statement of truth, the same care applies to them as to the report. Our guide to the statement of truth covers the wording and what a false statement can lead to.

Can an expert refuse to answer a Part 35 question?

Not on their own say-so. Where an expert believes questions are not properly directed to clarification, or were asked out of time, the CJC guidance (para 69) says they should discuss the questions with those instructing them and, if appropriate, those asking, and try to resolve the problem without an application to the court.

If there is no agreement and no party applies for directions, the expert can file a written request for directions under CPR 35.14. Unless the court orders otherwise, the expert must send the proposed request to the instructing party at least 7 days before filing it, and to all other parties at least 4 days before. Silence is the risky option, because the sanction for an unanswered question falls on the party who instructed the expert.

What happens if the expert does not answer?

Where a party has put a written question to another party's expert and the expert does not answer it, the court may order that the instructing party may not rely on that expert's evidence, or may not recover the expert's fees and expenses from any other party, or both (CPR 35.6(4)). The CJC guidance notes that continued non-compliance can lead to the party being debarred from relying on the report (para 67). That is why instructing solicitors chase answers hard, and why an expert who expects to be late should say so early.

Who pays for Part 35 questions?

The party or parties who instructed the expert pay the expert's fee for answering, whoever asked the questions. Paragraph 6.2 of Practice Direction 35 adds that this does not affect any decision of the court as to the party who is ultimately to bear the expert's fees. For a single joint expert, the instructing parties are jointly and severally liable for the expert's fees and expenses unless the court directs otherwise (CPR 35.8(5)).

Cost is also why proportionality matters. Answering a long set of questions can take an expert days, at the instructing party's expense, before any question of costs between the parties is decided. Experts should record the time spent on answers separately, so the fee note shows what the questions cost.

How do Part 35 questions fit with the joint statement?

Questions and the experts' discussion do different jobs. Questions clarify one report. A discussion under CPR 35.12 asks the experts to identify and discuss the expert issues and, where possible, reach an agreed opinion, and the court can direct them to prepare a statement of the issues on which they agree and disagree, with a summary of their reasons.

Where the timetable puts questions first, the answers become part of the report the experts discuss, so a clear answer can take an issue off the agenda. Where a report has gaps, Mustard v Flower suggests a supplementary report or the joint discussion is often the better tool. Our joint statement checklist covers that stage, and our guide to writing an expert witness report covers how to write a report that draws fewer questions in the first place.

How ALLDOQ fits

Answering Part 35 questions well means getting back to the evidence quickly: the paragraph that made the statement, the entry that supports it, and the page that entry sits on. ALLDOQ gives medico-legal experts one secure workspace for each instruction: the records and instructions in one place, a chronology with every entry linked to its source page, a report builder and time recording for the fee note. Book a walkthrough to see it on a real instruction.

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