Part 35 Questions: How to Trip Up the Defendant's Expert

Part 35.6 of the Civil Procedure Rules gives you a powerful weapon that far too many claimant teams leave in the drawer. You can put written questions to the defendant's expert within 28 days of receiving their report, and the answers become part of that report. This is not a courtesy exercise. It is cross-examination on paper, and if you do it properly, you can unravel a weak expert opinion before you ever set foot in court.

The trick is knowing what to ask. A defendant's surveyor will often note damp or mould but attribute it to tenant lifestyle or condensation without any evidential basis. Your questions should force them to explain their reasoning. Ask what specific evidence they relied upon to exclude a structural cause. Ask whether they inspected the exterior of the property. Ask if they reviewed the landlord's repair records and what they found. Under Griffiths v TUI UK Ltd [2021] EWCA Civ 1442, an expert must set out the factual basis for their opinion. If they cannot do so when challenged, their evidence loses credibility.

Focus on the timeline. Defendant experts routinely minimise the period of disrepair because that directly affects quantum. If your client says the leak started in January 2023 and the expert says June 2024, put the question directly. Ask what documents or inspection findings support their later date. Ask whether they considered the claimant's witness evidence at all. If they admit they did not, you have just handed the judge a reason to prefer your expert.

Do not waste questions on matters that do not move the case forward. You are limited to questions that seek clarification of the report, so asking argumentative or rhetorical questions will be struck out or simply ignored. Be surgical. Every question should either close down an escape route or extract an admission you can deploy at trial or in negotiation.

The answers must be provided within 28 days unless the court directs otherwise. If the expert fails to answer or gives evasive responses, Part 35.6(3) allows the court to order that their evidence cannot be relied upon. I have seen cases where a landlord's entire defence collapsed because their expert could not justify basic conclusions under written questioning. That is the outcome you should be aiming for every time you receive a report that does not add up.