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Understanding the Range of Opinion (RoO) - Dr Mark Burgin

16/11/21. Dr. Mark Burgin BM BCh (oxon) MRCGP describes some of the difficulties that experts encounter when trying to describe a range of opinion.

There are three main reasons why many reports do not include the mandatory range of opinion (RoO) – the expert lacks experience, they believe that there is single right answer or the issue is not material.

For the solicitor instructing an expert to address a RoO an awareness of these issues can help them make reasonable adjustments to support the expert.

There are three parts of the RoO – the two hired gun opinion for claimant and defendant and the expert’s opinion including reasoning.

Gentle questioning can improve the quality of the expert’s range of opinion and avoid the expert being accused of working as a hired gun.

Lack of experience

Despite being mandatory the CPR35 RoO is found in less than 1% of PI reports are even where several RoO required few experts will offer more than one.

Experts cite lack of experience of offering a RoO as a major barrier to offering RoO in their reports and they do not know what other experts think on this issue.

When a RoO is provided it frequently misses out one or other end of the range or fails to clarify where the expert’s opinion falls on the range.

I recommend that solicitors take opportunities to ask for a range of opinion whenever there is a difference in the opinions between experts.

Single right answer

Many experts write their report as if their opinion is the correct one and other opinions do not need to be considered, some also believe this.

Experts find it hard to understand that a court needs to understand both (or all) sides of the argument to make their decision.

To find a single answer the expert will have made assumptions about the material facts that the court may disagree.

The expert may not realise that court needs to unpick the expert’s reasoning to ensure that the decision is based upon the facts as the court finds them.

Not material

Some experts prefer not to offer any opinion on the issue believing that it is not important to the court (or will weaken the expert’s opinion).

Experts say that they are should not try to decide a dispute which is correct but then fail to offer any assistance to the court on the dispute at all.

This creates problems for the court which is left trying to decide the issues without an expert and could lead to the court being critical of the expert.

It can be difficult to get an expert to engage with what they see as not material issues so I recommend presenting it to the expert as an intellectual puzzle.


A range of opinion is mandatory where there are issues in dispute and a separate RoO is required for each issue in dispute.

This means that the majority of expert reports are technically in breach of PD35 3.2 (6) and solicitors have the option to point this out when returning reports.

Without a range of opinion the report is easier to challenge and the expert does not look as independent but will most will survive.

Solicitors should ensure that their expert has the experience needed to write a good range of opinion when it is necessary.

Doctor Mark Burgin, BM BCh (oxon) MRCGP is on the General Practitioner Specialist Register.

Dr. Burgin can be contacted on This email address is being protected from spambots. You need JavaScript enabled to view it. and 0845 331 3304 website

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