A recent Upper Tribunal decision gives some unusually practical guidance for experts who rely on material found online.

In SU (Expert reports – format) Bangladesh [2026] UKUT 317 (IAC), the Tribunal considered expert reports which drew heavily on publicly available internet material. The decision is particularly useful because it deals with something that now affects experts in many fields: how to use online source material properly in an expert report.

The Tribunal’s guidance is fairly straightforward, but important.

Where an expert relies on material found online, the source should be identifiable and capable of being checked. So far as possible, the expert should use the primary source rather than a secondary report about it. If material is quoted, it should be clearly identified as a quotation, with a link to the source and a translation where appropriate.

That is the sourcing side of the exercise.

But there is a separate point which is perhaps more important.

The material found online is not the expert opinion.

It is source material from which the expert may form an opinion.

The expert’s task is to consider that material, explain its relevance and significance, and then form and express an independent opinion based on it.

Both parts matter.

The underlying source material must be sufficiently transparent for the court or tribunal to understand where it came from and, where necessary, check it. But the report must also show the expert’s reasoning. The court needs to be able to understand how the expert moved from the underlying facts and sources to the opinion ultimately expressed.

It is then for the court or tribunal to decide what weight to give that opinion.

Primary sources matter

One point made expressly by the Upper Tribunal is that experts should, where possible, go back to the original source.

That may sound obvious, but it is increasingly easy to rely on a newspaper article, online summary, social media post or another secondary source which itself refers to an underlying document.

For an expert, that can create unnecessary uncertainty.

If a government statement, NGO report, technical paper, regulatory document or other primary material exists, there is obvious value in identifying and considering that material directly.

The Tribunal also stressed the importance of making quotation clear. Material copied from elsewhere should not appear in the report as though it were the expert’s own words.

That is not simply a matter of presentation. It enables the reader to distinguish between:

• the underlying source;
• the facts or information derived from it;
• the expert’s analysis of that information; and
• the expert opinion.

Those distinctions are central to a properly reasoned expert report.

The Academy’s own guidance on the Model Form of Expert Report reflects the same need to distinguish clearly between matters of fact and opinion.

Applying the material to the case

The Tribunal also made clear that a report should do more than set out general material.

Where the expert has been asked to consider the particular circumstances of a party, the report should apply the expert’s general conclusions to those particular facts.

That is an important part of what makes the evidence expert evidence rather than simply research.

A court can often read source material for itself. The value of the expert lies in the specialist analysis and opinion brought to that material.

That may involve explaining technical significance, identifying limitations, placing information in context, drawing on professional experience or explaining how apparently conflicting material should be understood.

The Academy’s What is an Expert Report? guidance similarly stresses that an expert report is not merely a statement of conclusions. The factual basis and reasoning leading to the opinion matter.

Responding to criticism

There is another useful practical point in SU.

Where one of the parties has raised concerns about an aspect of the expert report, the Tribunal said the expert should address those concerns directly, bearing in mind the overriding duty to assist the Tribunal on matters within the expert’s expertise.

That matters because an expert’s duty is not to defend the report at all costs.

If a legitimate criticism identifies an error, omission, weak source or assumption which needs reconsideration, the expert should deal with it.

The Academy’s Code of Practice for Experts places independence, impartiality, objectivity and integrity at the heart of expert practice.

A practical consequence of the online world

The volume of information available to experts has changed enormously.

In many fields, an expert can now locate hundreds of sources in a relatively short period. That can be extremely useful, but volume is not the same as quality.

The discipline lies in showing:

• what material has actually been relied upon;
• where it came from;
• why it is relevant;
• what the expert makes of it; and
• how it contributes to the opinion expressed.

That is why traceability matters.

The court or tribunal does not simply need an expert who can find information. It needs an expert who can analyse that information, explain it and give a properly supported opinion within their expertise.

That is the useful lesson from SU (Expert reports – format) Bangladesh.

Decision:
https://tribunalsdecisions.service.gov.uk/utiac/2026-ukut-00317

BAILII:
https://www.bailii.org/uk/cases/UKUT/IAC/2026/317.html

Related Academy resources

• Model Form of Expert Report
• What is an Expert Report?
• Code of Practice for Experts
• The Expert’s Report training

The High Court’s judgment in Various Claimants v Mercedes-Benz Group AG and others [2026] EWHC 1753 (KB) is a useful reminder that technical expertise, however impressive, is only part of the job of an expert witness.

The litigation involved a huge amount of highly technical expert evidence across a number of disciplines. What is particularly interesting is the contrast in the judge’s assessment of the experts themselves.

Some were praised for the quality and fairness of their evidence. Others attracted criticism over aspects of their compliance with Part 35.

That contrast matters because the experts involved were not lacking in technical expertise. They were experienced specialists dealing with complex issues in major litigation.

The point is rather that being an expert in your field and being an effective expert witness are not quite the same thing.

Under CPR Part 35, an expert’s role is to assist the court on matters within their expertise. That duty overrides any obligation to the person instructing or paying them.

Practice Direction 35 goes further. Expert evidence should be the independent product of the expert, uninfluenced by the pressures of litigation, and experts should consider all material facts, including those which might detract from their opinions.

Those requirements affect far more than the declaration at the end of a report.

They affect how the expert approaches the evidence in the first place.

An expert needs to be able to distinguish between what they know, what they have been told and what they have inferred. They need to consider material which may not support the position of the party instructing them. They need to explain the basis for their conclusions and, where appropriate, acknowledge that there may be a legitimate range of professional opinion.

Perhaps most importantly, they need to remain willing to reconsider their conclusions as the evidence develops.

That may sound elementary to experienced expert witnesses. But the significance of the Mercedes-Benz judgment is that these issues arose in extremely sophisticated litigation involving highly experienced specialists.

The technical complexity of the subject matter did not lessen the importance of the expert’s procedural and professional duties.

If anything, it made them more important.

Where the underlying issues are difficult for a court to evaluate without specialist assistance, the court is particularly dependent upon the expert presenting that specialist knowledge independently, fairly and in a way that can be understood and tested.

That is why the quality of expert evidence cannot be measured simply by the expert’s qualifications or standing in their profession.

The court also needs to be able to trust the process by which the opinion has been reached.

The Academy’s guidance on party-appointed experts reflects this. The expert’s role is to provide unbiased opinion within their expertise and not to assume the role of advocate.

The Academy’s Code of Practice for Experts similarly places independence, impartiality, objectivity and integrity at the centre of expert practice.

And because much of the expert’s evidence will ultimately be contained in the report, the Academy’s Model Form of Expert Report is designed to help experts present their reasoning in a form which assists the court. The Academy’s The Expert’s Report training also deals specifically with compliance, professional guidance and the practical preparation of expert evidence.

The broader lesson from the Mercedes-Benz litigation is fairly simple.

An expert witness brings two kinds of expertise to court: expertise in their professional field, and expertise in performing the role of an expert witness.

The first does not automatically provide the second.

Judgment

A High Court decision provides a useful warning for professionals who become expert witnesses in matters in which they have already been involved.

In MSA Properties Ltd v The Drapery Northampton Ltd [2026] EWHC 1420 (KB), the court had to resolve a dispute concerning deteriorated structural joists in a building in Northampton. Both parties relied on structural engineering evidence.

The point of wider interest for experts concerns the defendant’s expert, who had already been involved in the matter before the litigation.

He inspected the building in 2023 and produced a report for the defendant. That report was not prepared as expert evidence for the proceedings. By 2025, however, he was acting as the defendant’s expert witness.

That change of role became important.

The judge noted that the later expert report did not refer to the earlier inspection or the report produced at the time, despite the expert accepting in oral evidence that the earlier inspection had given him a better view of the joists.

The court was also critical of the extent to which he had engaged with the available evidence and of the opportunities available to him to inspect the property more fully.

The most significant criticism was the judge’s observation that his approach reflected:

“some conflation of his role as a contractor engaged in negotiations with the Claimant and his duties as an expert witness”

There was no suggestion that the expert had deliberately acted partially. The concern was rather that aspects of his earlier role appeared to have carried over into the way he approached his later expert evidence.

That is a useful warning for any professional who changes role during the life of a dispute.

Previous involvement does not automatically prevent someone from later acting as an expert witness. In some cases, that earlier involvement may mean they have valuable knowledge of the subject matter.

But the nature of the role changes.

A contractor, consultant or adviser may previously have been helping a client solve a problem, negotiate a position or achieve a particular commercial outcome. An expert witness has a different duty.

Under CPR 35.3, an expert’s duty is to help the court on matters within their expertise. That duty overrides any obligation to the person from whom they have received instructions or by whom they are paid.

That is not simply a formal statement to be repeated in the declaration at the end of a report. It has practical consequences for the way an expert approaches the evidence.

Transparency about previous involvement

Where an expert has already inspected the subject matter, produced reports, advised a party, taken part in negotiations or expressed views before being instructed as an expert witness, that history may be material to the opinion now being given.

The point is not that every earlier conversation or document must automatically be reproduced. It is that relevant prior involvement should not be left invisible if it bears on the expert’s present reasoning.

That is particularly important because CPR 35.10 requires an expert report to state the substance of all material instructions, whether written or oral, on the basis of which the report was written. Practice Direction 35 also requires the expert to make clear which facts are within their own knowledge and which have been provided by others.

In this case, the earlier involvement was not peripheral. The expert had inspected the joists at a time when they were more fully exposed and had produced an earlier report. He later accepted that the earlier inspection had given him a better view of the joists, yet neither the inspection nor the earlier report appeared in his expert report.

That is a useful illustration of why disclosure matters.

If earlier involvement has informed what the expert knows, assumes or concludes, the court should be able to see that route clearly. If it only emerges later, particularly in cross-examination, the omission can create an avoidable question about the completeness and transparency of the expert’s reasoning.

For an expert changing role, a sensible question at the outset is:

What have I already done, seen, said or concluded in this matter, and what of that is material to the opinion I am now giving?

If someone changes role during the life of a dispute, earlier assumptions may need to be revisited. Previous opinions should not simply be carried forward without being tested against the evidence now available. Earlier inspections, reports and involvement may themselves be relevant and should be dealt with openly where necessary.

The wider framework of the Civil Procedure Rules matters as well.

The overriding objective in CPR 1.1 is to enable the court to deal with cases justly and at proportionate cost. Expert evidence forms part of that process. It is therefore not enough for an expert merely to possess relevant expertise. The evidence has to assist the court in a way which is independent, properly reasoned and proportionate to the issues in dispute.

That is why a change in role can be important.

A professional may quite properly have spent months or years advising a client, negotiating with another party or working towards a particular practical outcome. Those activities may require judgement, persuasion and a close identification with the client’s interests.

The expert witness role is different.

Once instructed as an expert, the professional must be able to step back from that earlier involvement and approach the evidence independently. That may mean reconsidering previous views, acknowledging matters which do not support the client’s position and making clear where earlier involvement has informed the present opinion.

• The Academy’s guidance on party-appointed experts explains the overriding duty owed by an expert to the court.
• The Academy’s Code of Practice for Experts places independence, impartiality, objectivity and integrity at the heart of expert practice.
• The Academy’s Model Form of Expert Report is also relevant where an expert has had previous involvement, because the report should make clear the factual basis of the opinions expressed and the material relied upon.

The lesson from MSA Properties is not that previous involvement disqualifies an expert. It is that a professional who moves from contractor, adviser or negotiator to expert witness must make that transition consciously and transparently. The court may look closely at whether the expert has genuinely separated the new role from the old one, and whether the report gives a clear account of any earlier involvement which bears on the opinion now being expressed.

For experts, that is a useful point to consider before accepting instructions in a matter in which they have already been involved.

See the judgment here on BAILII.

Anthropic has just announced that Claude will start leaving an invisible mark in the text it generates, in an announcement that may have unintended consequences for expert witnesses.

Supported Claude models will embed machine-readable watermarks into generated text. Anthropic says those marks will travel with the words when copied and pasted into other documents and may survive subsequent editing.

The immediate purpose is provenance. As the volume of AI-generated material increases, watermarking offers a potential means of identifying content that has passed through a particular AI system.

For expert witnesses, however, that raises a rather more difficult question: if an expert report contains an AI watermark, what exactly does that prove?

Perhaps less than might first appear.

Detection is not the same as authorship

One of the most important qualifications comes from Anthropic itself.

Anthropic cautions that detecting its watermark does not establish that Claude wrote or originated the material. Rather, it indicates that the content may have been processed by Claude.

That distinction could be particularly important in expert evidence.

An expert might write an entire report themselves and subsequently ask an AI tool to correct spelling and grammar. Another might use AI to improve the structure of material they have already written. A third might provide their analysis and ask an AI system to turn it into polished prose.

Those activities are quite different from asking an AI system to examine the underlying evidence, perform the analysis and suggest the opinion the expert should express.

Yet all involve AI-generated or AI-processed text.

Consider four possible uses:

• An expert writes their report and uses AI to check spelling and grammar.
• The expert writes the substance but asks AI to improve its structure or expression.
• The expert provides their analysis and asks AI to draft passages expressing it.
• The expert asks AI to analyse the evidence and assist in formulating the opinion.

All involve AI, but they plainly do not raise the same questions about the independence of the expert’s analysis and opinion.

That makes the presence of a watermark potentially useful evidence, but not necessarily evidence of what might initially be assumed.

Provenance of the text is not provenance of the opinion

This is perhaps the central issue for expert witnesses. A watermark may provide evidence about the provenance of the words. It might indicate that Claude, or another AI system using similar technology, has been involved in generating or processing them:

• It cannot, by itself, establish the provenance of the opinion.
• It does not tell us who examined the evidence.
• It does not tell us who identified the relevant issues.
• It does not tell us whether the expert carried out the underlying calculations or analysis.
• And, most importantly, it does not tell us whether the conclusion was independently reached by the expert or suggested by an AI system.

The same paragraph could conceivably carry an AI watermark whether Claude corrected three grammatical errors in it or generated the paragraph from scratch.

For expert evidence, those are very different propositions.

The absence of a watermark proves little too

There is also a problem in the opposite direction.

No watermark does not necessarily mean no AI.

Anthropic acknowledges that detection can become more difficult where generated material has subsequently been heavily edited, paraphrased, translated or combined with other text. A passage may also simply be too short to provide sufficient information for reliable detection.

This creates an important limitation if watermark detection ever begins to be used when examining expert reports.

A positive result may indicate AI involvement without establishing the extent or nature of that involvement whilst a negative result cannot necessarily establish that there was no AI involvement at all.

Watermark detection should therefore not be treated as a binary test of whether an expert “used AI”.

A new question in cross-examination?

The development also raises an interesting practical possibility.

“Your report contains a watermark indicating that it was processed by Claude. How did you use it?”

The answer might be entirely unremarkable.

The expert might explain that they wrote the report themselves and used Claude to check its grammar. They might explain that they used it to condense a lengthy passage they had already written. Alternatively, the answer might reveal that AI played a much greater role in analysing material or formulating the opinions contained in the report.

The takeaway is that whilst the watermark itself cannot distinguish between those situations, it may, however, provide the starting point for questions which can.

That means the increasingly important question may not simply be:

“Did you use AI?”

It may instead be:

“Precisely how did you use it?”

Watermarking is becoming a real technology

Anthropic is not alone in pursuing this approach.

Google has already developed SynthID Text, a watermarking technology for AI-generated text. Rather than inserting a visible label or conventional metadata, SynthID subtly affects the model’s choice of tokens as text is generated. Across a sufficiently long passage, those choices create a statistical signature which can subsequently be detected.

Anthropic has not publicly confirmed that Claude’s watermark uses the same technical method, so the two systems should not be assumed to work identically.

The significance is broader. Text watermarking is moving beyond academic research and into mainstream generative AI products.

If the technology becomes widespread, lawyers, courts and experts may increasingly encounter claims that a document has been identified as having passed through an AI system.

Understanding what such a finding does, and does not, establish will therefore become important.

The expert remains responsible

The Academy’s guidance on the use of Artificial Intelligence by expert witnesses already addresses the more fundamental issue.

AI can be a useful tool, but it cannot substitute for the expert’s own expertise, analysis and opinion. Experts remain responsible for the evidence they give. Where AI has played a significant role, keeping appropriate records of how it was used may also become increasingly important, particularly if the expert is subsequently required to explain that use in court.

Watermarking adds another dimension to that responsibility.

It may make some uses of AI more readily identifiable. But identifying that an AI system touched the words is not the same as establishing who produced the intellectual work behind them.

For expert evidence, that distinction is crucial.

Provenance of the text is not necessarily provenance of the opinion.

As AI provenance technology develops, the ability of an expert to explain what the AI did, what the expert did, and where the opinion actually came from may become increasingly important.

In Trinsic Collagen Ltd v Procoll Ltd [2026] EWHC 1793 (Ch), the court criticised the way additional information had been provided to the claimant’s experts and then relied on without being clearly identified in the reports, or in one instance the joint statement.

The issue was not that the experts had spoken to the client. It was that the factual basis of their conclusions was not always transparent.

For an expert report to assist the court properly, the reader should be able to see the route from the facts and assumptions, through the analysis, to the opinion reached. That means being clear about material obtained through discussions, site visits, correspondence or subsequent instructions, especially where it influences the expert’s reasoning.

The Academy’s own guidance reflects the same principle. An expert report should contain a concise statement of the facts and assumptions used, followed by the expert’s analysis and opinion, with fact and opinion clearly distinguished.

A useful question before signing a report is this: could another expert, or the judge, identify every material fact and assumption on which my conclusion depends? If not, the report may need another look.

The Academy’s Model Form of Expert Report also reflects this approach.

Not later. In the report.

If an expert opinion depends on incomplete data, assumptions or qualifications, those limitations belong in the written report.

1. Not in cross-examination.
2. Not in re-examination.
3. Not only after the tribunal asks the right question.

In Mew v General Dental Council [2026] EWHC 1116 (Admin), the High Court considered expert evidence given during professional disciplinary proceedings.

One expert had deliberately avoided setting out limitations in the available data, believing that they could instead be explained when he gave oral evidence.

Charles Bagot KC, sitting as a Deputy High Court Judge, said that this revealed a “fundamental misunderstanding” of the obligations of a CPR-compliant expert.

The problem was not that the evidence required qualification. Many expert opinions do.

The problem was that the qualification had been withheld from the report.

A court or tribunal must be able to understand:

• what the expert can conclude;
• what the expert cannot conclude;
• where the evidence is uncertain; and
• how those limitations affect the strength of the opinion.

A carefully expressed qualification does not weaken expert evidence. It allows the decision-maker to assess it properly – and will often make the opinion more credible.

The expert report should contain the opinion the expert can genuinely support, not an unqualified version that appears more persuasive on first reading.

Read the judgment:
https://www.bailii.org/ew/cases/EWHC/Admin/2026/1116.html

Expert witnesses play a key role in the justice system and it has always been the case that expert reports and other documents referred to in court were in the public domain. But getting hold of them has not been straightforward and concerns were raised in Lady Hale’s judgment in Cape Intermediate Holdings Ltd v Dring [2019] UKSC 38 a  case relating to asbestos exposure. This set out something of a mish-mash of practices and rules and the issue, together with the increasing reliance on electronic court bundles gave rise to the work of  Transparency and Open Justice Board.

The resulting Access to Public Domain Documents Pilot, postponed from earlier this year, will now go live on 1^st January 2026, initially for year. Details of the pilot are set out in Practice Direction 51ZH but the key points that experts should take note of are as follows;

• Pilot covers Commercial Court and London Circuit Commercial Court of the King’s Bench Division and  the Financial List (Commercial Court and Chancery Division) only.
• It affects any documents that have already been filed with the court and which are then relied on in court from January 2026, not just new documents.
• Affected documents include expert reports and annexes and appendices to expert reports;
• Expert reports these must be filed within 14 days of being relied on (submissions, skeletons within 2 days).

Filing of reports will be the norm, exceptions require a Filing Modification Order or FMO to be applied for.

In summary while expert reports were always theoretically available to non-parties access should become a great deal easier, see the Academy website for more detailed guidance.

Only time will tell whether the press or public will have an appetite for reading sometimes complex and lengthy reports on forensic accounting, construction or IT but experts should make sure, as always, that their opinions are properly supported, reasoned and consistent with their previous opinions – remembering that any report that has been filed will potentially become available through the pilot if used in hearing!

The Academy responded to the consultation for the pilot and continues to engage with the judiciary and legal profession on this and other issues to ensure that expert views are taken into account and that members have access to the best possible advice and guidance.

Our Judicial Committee publishes the authoritative guidance for experts so you can be sure that you are adopting best practice. This includes for example the Model Form of Expert’s Report and Guidance Notes on Meetings of Experts, Contingency Fees & Remote Evidence.

We also provide practical advice and guidance on topics such as GDPR, Joint Statements, privilege and so on which is available at no charge to members in the Academy’s Knowledge Hub.

Members can also call our Technical Helpline for help and advice on ethical and practical issues from dealing with instructions to getting paid.

The Criminal Procedure Rules Committee have issued a new consolidated set of the Criminal Procedure Rules which came into force on 6^th October 2025.

The Criminal Procedure Rules 2025 replaces the Criminal Procedure Rules 2020 and incorporates the 9 sets of amendments made since the 2020 rules were published. The Committee has also published a guide to the new Rules. criminal-procedure-rules-2025.pdf

In addition, the Criminal Procedure Rules Committee have just published the. Fourth Amendment to the Criminal Practice Directions 2023 – November 2025 – Courts and Tribunals Judiciary. The changes, some of which will impact on experts in Chapter 7, come into force on 18^th November 2025.

The amendments:

1. require the disclosure in an expert report of any authoritative advice or warning relevant to the content of the report;
2. require the disclosure in an expert report of any past adverse finding or disciplinary proceeding, even if since resolved; and
3. ensure the compatibility of the declarations of compliance required by (i) the Criminal Practice Directions, and (ii) the Forensic Science Regulator’s statutory code of practice.

Updated Expert Declaration
In addition to the changes outlined above there are also changes that need to be made to the Expert’s Declaration, full details are on the Academy website.

 

Don’t forget to update any templates you have that are effected by the changes and to satisfy yourself that any report issued after 18^th November 2025 complies with the new requirements.

Most people will be aware by now that a pilot scheme for “access to public domain documents” in the Commercial Court, London Circuit Court and the Financial List is due to start in October.  Guidance and details of the pilot aren’t out yet but it’s expected that at least some expert reports will become publicly available.

In the meantime experts who are concerned about the possibility should start to think about making sure the opinions they provide are consistent, not just within a given report but within all their reports. Of course that’s not really a new requirement and from time to time an expert will be challenged to explain why their opinion today seems to differ from a previous opinion.

That’s exactly what happened in Abbott Diabetes Care v Sinocare a trademark dispute about the design of an ‘on-body’ glucose monitor. The Defendant’s market research expert had examined surveys conducted by the Claimant ‘s expert who unfortunately was unable to testify because of ill-health.  This placed more emphasis than normal on her evidence which was critical of the approach used in the surveys that supported the claim.

She was also challenged to explain why her opinions appear to vary in this case compared to her views on what the claimant’s counsel viewed as an equivalent survey in Tesco v Lidl. Fortunately she appears to not only have held entirely consistent views but was well-prepared enough to, as the judge explained “emphatically and, in my view, convincingly, rejected the suggestion that there was no material difference between the Traditional Survey and the Lidl survey.”

What this case does emphasis is firstly the need  to be objective and consistent  between cases and in the light of the impending Open Justice pilot experts should add a new question to their internal checklist. Not only should they ask ‘what would I say if were on the other side’ but ‘is this the same opinion that I gave last time and if not, why not?’

Secondly if you have appeared in court and your evidence has been discussed (or from this year made public in full)  you would be well advised to read up on any relevant cases before giving evidence!

The Academy’s Knowledge Hub. includes practical advice and guidance for experts who want to check their practe, including for example the Model Form of Expert’s Report and Guidance Notes on Meetings of Experts, Contingency Fees & Remote Evidence. As a member you can also call our Technical Helpline for help and advice on ethical and practical issues from dealing with instructions to getting paid.

 

Being instructed as an expert witness can be an interesting and fulfilling aspect of professional life, but it’s not without its challenges. One of the most common (and under-discussed) issues experts face is how to manage their instructing solicitors.

It’s easy to assume that once you’re engaged, expectations are fixed and your role is simply to deliver. But in reality, managing your instructing solicitor is a key part of ensuring that what you deliver is useful, compliant, and capable of standing up in court.

Academy Council Member Helen Gregory of Opus Forensic Accounting has helpfully provided her five top tips for how expert witnesses can work most effectively with their instructing solicitors.

1. Be realistic about deadlines — and say no if needed

There’s a temptation to take on every instruction that comes your way, particularly if you’re self-employed and don’t know where the next one is coming from. But accepting unrealistic deadlines can cause problems for all involved. Rushed reports are more likely to contain errors, lack clarity, or fail to meet procedural requirements. And in the worst-case scenario, they can be thrown out by the court entirely.

It’s better to decline a job than to submit something half-baked. Be clear at the outset about what’s feasible and remember to factor in time not just for writing the report, but for reviewing documents, requesting further information, meetings with the solicitor and client, responding to queries, and navigating any surprises.

2. Build in contingency: Something will crop up

In theory, you receive a neat, complete bundle of documents and a clear brief. In practice, things are rarely that tidy. Documents arrive late or in multiple batches, some are missing or out of order, and the questions you need to address will take time to answer.

You need to allow for contingency: time to request clarifications, review additional information, and think critically about what you’re being asked to do. The more flexibility you build in, the more likely you are to produce a report that is robust, complete, and helpful to the court.

3. Understand the limits of your visibility

One key challenge is that, as an expert, you often operate in isolation from the wider case. You may see only a snapshot of the full picture. It’s important to remain focused on your instructed area and resist the temptation to speculate beyond it.

At the same time, remember that lack of context doesn’t remove your duty of care. If documents appear incomplete, if your opinion feels influenced, or if something doesn’t sit right, you must raise it. You are reporting to the court, not acting as an advocate for either party.

4. Deliver bad news where it’s warranted

It’s not always easy to say your client doesn’t have a case. But as an expert witness, you have a duty to give your honest, professional opinion, even if that opinion isn’t what the instructing solicitor wants to hear.

Be aware that some may (consciously or otherwise) attempt to steer your opinion. Stay alert to missing evidence, biased questions, or subtle attempts to frame a narrative. Your integrity and credibility depend on your ability to remain independent and evidence-based.

5. Know the rules and review your report thoroughly

Expert reports must comply with the relevant Civil, Criminal or Family Procedure Rules. That includes formatting, content, and declarations. A technical report that omits the correct statement of truth or includes the wrong version risks being ruled inadmissible.

It’s also essential to re-read what you’ve written. That may sound obvious, but when deadlines loom and multiple drafts are flying around, it’s easy to miss a critical detail. The best option is to ask someone else unconnected to the case to read and cast it, but that may not always be possible so do make time to review your own work with a clear head.  You may be cross-examined on your report, so make sure you’re comfortable defending it.

Final thoughts

Whatever your discipline, acting as an expert means more than just knowing your subject. It requires planning, time management, self-awareness, and the confidence to push back when needed.

Clear communication with instructing solicitors, realistic boundaries, and careful preparation are vital. If in doubt, The Academy of Experts offers training, guidance and support to help navigate the more complex aspects of expert witness work.

Helen is a Partner at Opus Forensic Accounting, part of the Opus Business Advisory Group, and brings over 25 years’ experience in civil and criminal investigations, commercial disputes, and matrimonial matters. A trusted expert witness and active figure in the sector, including roles with The Academy of Experts and the South West Fraud Forum, she recently joined Opus, a national advisory firm with 14 offices, 35 Partners, and specialist divisions spanning restructuring, strategic advisory, forensic accounting, and equity.