An expert may have sound reasons for favouring a particular answer. But explaining those reasons is only part of the task. Where there are competing opinions, the report also needs to show that they have been considered fairly, including the evidence which does not sit comfortably with the expert’s own conclusion.

JBX v Frimley Health NHS Foundation Trust [2026] EWHC 2294 (KB), decided on 4th September, 2026 by Andrew Kinnier KC, sitting as a Deputy Judge of the High Court, concerned damages following admitted clinical negligence. One issue was future care and accommodation for a profoundly brain-injured claimant.

What the court found

The judge identified two particular concerns about the claimant’s neuropsychiatric evidence:

• The expert favoured home care but had inadequately examined its disadvantages and the advantages of residential care.
• The judge criticised his persistence with a diagnostic opinion outside his expertise.

As a result, the defendant’s evidence was preferred on disputed neuropsychiatric matters (paragraphs 95–97).

Similar problems affected the claimant’s care evidence.

• A letter acknowledged “positives and negatives” but listed only home care’s benefits and residential care’s drawbacks.
• The judge found the overall approach one-sided (paragraphs 113–114).

Both care experts were giving oral evidence for the first time. Despite the defendant’s expert’s marked nervousness, her report assessed competing options with reference to medical evidence. Her evidence was preferred where they disagreed (paragraphs 112–117).

The reporting requirement

In civil proceedings in England and Wales, Practice Direction 35, paragraph 3.2(6), requires an expert’s report to summarise the range of opinion, where one exists, and give reasons for the expert’s own opinion. Paragraph 2.3 requires consideration of material facts which might detract from that opinion, while paragraph 2.2 requires objective, unbiased assistance rather than advocacy.

There is a practical difference between those requirements. An expert might describe several professional approaches yet omit an inconvenient fact. Equally, a report might accurately record the facts but give no meaningful account of why another expert could interpret them differently. Both the evidential material and the competing analysis need attention.

This sits within the overriding duty under CPR 35.3 to assist the court on matters within the expert’s expertise. That duty takes precedence over obligations to the person instructing or paying the expert. A useful way of approaching the report is therefore to ask what the court needs to understand, rather than what makes the instructing party’s position easiest to defend.

Considering an alternative does not mean endorsing it

For example, suppose a building expert recommends replacing a defective component rather than repairing it. The report could explain why replacement would solve the problem, then dismiss repair as inadequate. A more useful comparison would identify what the proposed repair could achieve, the assumptions on which it depends and the evidence that causes the expert to reject it. The disadvantages of replacement, such as disruption or unnecessary intervention, would also need examination where they matter to the issue being addressed.

That exercise might leave the opinion entirely unchanged. It would nevertheless give the reader a much clearer explanation of why it was made. Alternatively, it might reveal that a repair is viable in circumstances the expert had not initially considered, or that further investigation is needed before choosing between the options.

Experts must, therefore, be equally clear about the question they are answering. “I would choose X” and “Y is not reasonable” are different propositions. Explaining a preference does not, without further analysis, establish that another approach falls outside a reasonable range.

This is not an argument for artificial balance or equal space for every suggestion. A plainly inapplicable alternative may need only a short explanation. A credible competing approach to a central issue deserves more. As a practical drafting test, consider whether a reader could understand the strongest argument against your conclusion without having to reconstruct it from the other side’s report.

Make the reasoning available to the reader

The Academy’s Model Form of Expert Report distinguishes facts, assumptions and opinions, including opinions taken from other experts. It also emphasises linking conclusions to the supporting text. Those distinctions help readers follow the reasoning rather than simply being asked to accept the author’s assurance that the necessary work has been done.

In practice, it is worth checking the route from each important conclusion back to its supporting material.

• Which observation, calculation or professional judgment carries the conclusion?
• What would change if an assumption proved wrong?
• Does the report explain why apparently contrary material does not alter the answer?

An appendix can contain the underlying detail, but the reader still needs to be shown how that detail affects the opinion.

Care is also needed where the reasoning depends on another discipline. The Model Form distinguishes between opinions of others on which the writer relies in forming their own opinion and those the writer accepts but cannot comment on authoritatively. A clear report should make that dependence visible rather than allowing the reader to assume that every underlying conclusion has been independently assessed by its author.

Carry the analysis into the joint statement

The same care is needed when the experts discuss their differences. CPR 35.12 provides for court-directed discussions and a statement recording agreement and disagreement, with reasons for the latter. The Academy’s guidance on joint statements addresses how those issues and reasons can be presented usefully.

A statement that the experts continue to disagree adds little unless it explains why. The difference may concern an assumed fact, the suitability of a method or the weight attached to particular evidence. Identifying that difference precisely is more helpful than placing two firm conclusions alongside one another. It also gives each expert an opportunity to check whether the disagreement is as extensive as it first appeared.

Before signing a report or joint statement, try reading it from the position of someone who favours the alternative. Have their substantive reasons been addressed, or merely their conclusion rejected? The aim is not to make the expert less decisive, but to make the basis of the decision open to proper examination.

These aspects of presenting and evaluating expert evidence are also covered in the Academy’s The Expert’s Report training.

Read the full judgment in JBX v Frimley Health NHS Foundation Trust. The assessments of the neuropsychiatric and care evidence are at paragraphs 95–97 and 112–117 respectively.