The Range of Opinion: Why Experts Must Address the Full Spectrum of Opinion to Uphold Report Quality and Legal Standards

On 21.08.2026, Gordon Exall’s Civil Litigation Brief published two Expert Watch commentaries on the same day. One concerned a tribunal that attached “very little weight” to an expert report because of the way the expert had gathered information and because he had failed to examine primary source material. The other concerned an expert who had not set out the range of opinion on the issues addressed in his report. When challenged, his answer was that he usually dealt with the range of opinion in the joint statement.

Exall’s verdict was blunt. Experts frequently fail to comply with this duty, and the failure is often fatal to a party’s case.

That should not surprise anyone who regularly reads judgments on expert evidence. The duty to address the range of opinion is one of the clearest duties in the rules, yet it remains one of the most commonly overlooked.

What the rules require

Practice Direction 35, paragraph 3.2(6), requires that where there is a range of opinion on the matters dealt with in the report, the expert must clearly summarise that range and give reasons for his own opinion. The purpose is straightforward. The court needs to understand not only what the expert thinks, but where that opinion sits within the wider professional debate.

None of this is new. The principles set out in The Ikarian Reefer in 1993 already required an expert to consider material facts that detract from his concluded opinion. The Practice Direction made that obligation explicit and placed it firmly in the report itself, where the court and the opposing party can test it.

The joint statement is not the answer. By the time experts meet, each party has pleaded and disclosed its case based on the reports. If the range of opinion appears for the first time in the joint statement, it has been withheld from those who needed it earlier, including the instructing party deciding whether to fight or settle.

Why experts leave it out

In my experience, experts usually omit the range of opinion from their reports for three reasons. None is defensible.

The first is advocacy drift. An expert who has formed a view may start to treat the alternative view as wrong rather than as genuinely held. Acknowledging it can feel like conceding ground. It is not. A report that states the opposing school of thought fairly, and then explains why the author does not share it, is stronger, not weaker. It shows the court that the opinion has survived contact with its rivals.

The second is a narrow professional frame of reference. An expert who has spent a career in one unit, doing things in one way, may believe there is no range of opinion because he has not seen or applied other accepted strategies. That is a reason to be cautious about accepting instructions. It is not a reason to omit the paragraph.

The third is the belief that the range can wait until the joint statement. The expert in Exall’s commentary appeared to hold that belief. It is contrary to the rules.

Two ranges, and the need to keep them apart

In clinical negligence, the word “range” can refer to two different things. Reports often blur them.

The first is the Bolam range. Breach is judged by asking whether the clinician acted in accordance with a practice accepted as proper by a responsible body of practitioners in the field, subject to the Bolitho requirement that the practice withstand logical analysis. When I report on breach, my task is not to say what I would have done. It is to say whether what was done fell within the range of practice that a responsible body of upper gastrointestinal surgeons would accept.

A judgment from July this year, discussed in the same Expert Watch series, dismissed a claim precisely because the expert told the court what he would have done rather than applying the Bolam standard.

The second is the range of expert opinion on other questions in the case, including causation, where Bolam has no role. Reasonable experts may differ on whether an earlier operation would have avoided the outcome. Paragraph 3.2(6) requires me to say so, summarise the competing positions, and explain why I hold my own view.

An example from my own field illustrates the point. When a contained anastomotic leak follows oesophagectomy, many surgeons manage the case with drainage, antibiotics and nutritional support alone. Others may add stenting or endoscopic suturing. A report that presents either approach as the only proper practice misstates the discipline. The honest report sets out both approaches, explains which the index case called for and why, and accepts what cannot be known.

What compliance looks like

The paragraph does not need to be long. It needs to do its job.

It should identify the competing positions, anchor them where possible in literature or guidelines rather than assertion, state where the author’s opinion sits, and explain why the author prefers that view. It should engage with the strongest version of the contrary position, not a weakened version of it. If the range is genuinely narrow, the expert should say so and explain why.

This kind of candour strengthens a report. It demonstrates integrity and earns the court’s trust, especially where the expert’s own position is a minority one.

The reasons matter as much as the summary. “In my opinion the majority view is correct” is not enough. It neither summarises the range nor explains the reasoning. The court is entitled to know what evidence, experience and logic move the expert from the range of opinion to his own conclusion. A properly reasoned explanation shows care, discipline and respect for the court’s task.

Key takeaways