Courts are increasingly being asked to consider the role of artificial intelligence (AI) in expert evidence. Several recent judgments have criticised experts' use of AI, particularly where questions arise over authorship, analysis and professional accountability.
One such case is Cornwall Council v M & Ors [2026] EWFC 306, in which Her Honour Judge Flexman (HHJ Flexman) provided useful guidance on the distinction between acceptable and unacceptable uses of AI by experts. Her conclusion was that the expert's use of AI in drafting her report had crossed the line from administrative assistance into substantive authorship.
Facts of the case
Cornwall Council v M & Ors [2026] EWFC 306 concerned care proceedings involving three children brought by Cornwall Council. The local authority sought care orders. The children’s father opposed them, arguing that the children should return to his care or to members of the wider family.
An independent social worker was instructed as an expert witness and produced a parenting assessment, assessments of potential kinship carers and an addendum report.
This article focuses on the court's consideration of how these reports were produced. Specifically, the judge examined the expert's use of Microsoft Copilot in drafting her reports and whether, as a result, her evidence could be relied upon.
The expert’s initial explanation for using AI
The expert did not initially disclose her use of AI. However, following judicial questioning, she explained that Microsoft Copilot had been used within a secure organisational environment to organise information and assist with drafting.
She emphasised that:
- “Copilot did not generate evidence, undertake analysis or form conclusions.”
- “All analysis, interpretation and professional judgment are entirely my own.”
- “All content was reviewed, amended and verified by me prior to finalisation.”
HHJ Flexman subsequently invited the expert to explain in greater detail how AI had been used.
She observed: “There is a sliding scale of use from what is acceptable to what is not, and it is not always straightforward to differentiate between what might arguably be assistance with presentation and what in fact amounts to AI authorship.”
Acceptable use of AI
The expert confirmed that she had used digital transcription tools and Microsoft Copilot to summarise transcripts.
The judge regarded the use of AI for transcription, spelling and grammar correction as a relatively low-risk application. Such tools can improve efficiency and presentation without affecting the substance of the expert's evidence.
HHJ Flexman described these activities as falling within what would generally be regarded as acceptable practice.
Unacceptable use of AI
However, the court drew a clear distinction between administrative assistance and the generation of substantive report content.
The expert subsequently accepted that a kinship assessment had been generated by AI from her notes, although she maintained that the final product reflected her own professional opinion.
The judge was unconvinced. AI had not been asked to create an assessment independently. However, HHJ Flexman observed that it had been used to transform the expert’s source material into a completed report. She considered this a significantly higher-risk use of AI that affected the weight that could be attached to the evidence.
The court was particularly concerned that:
- The analysis, report structure, subheadings and overall presentation had been generated by AI.
- The tone and style differed noticeably from the expert's own written and oral evidence.
- AI drafting notes had been left within the report, suggesting inadequate human oversight.
- The report contained factual inaccuracies, making it unclear whether those errors originated in the expert's original notes or had been introduced during AI-assisted drafting.
The outcome of the case
In this case, HHJ Flexman concluded that the expert's use of AI had extended beyond presentational assistance and into substantive report generation. As a result, she was unable to place significant weight on the expert’s evidence.
However, the judge was careful to note that this conclusion was based not only on the use of AI, but also on wider concerns regarding the quality of the expert's evidence, which she described as “lacking in rigour and clarity of thought”.
In reaching her decision, the judge referred to the duties imposed on experts by the Family Procedure Rules. These include the obligations to identify the material relied on and explain the reasoning process. They must also verify that the opinions expressed are their true and complete professional opinions.
She said: “Although not drafted with AI models in mind, the use of AI could be akin to third party involvement, depending on the way in which it is used.”
She also referenced the January 2026 guidance issued by the Academy of Experts, which distinguishes between lower-risk uses of AI, such as language correction, and higher-risk uses involving substantive analysis or content generation.
What can experts learn from this case?
This case provides an important reminder that expert witnesses remain personally responsible for every aspect of their evidence, regardless of whether AI tools have been used during its preparation.
Experts may be able to use AI safely for lower-risk administrative tasks, such as transcription, document organisation, spelling and grammar correction. The further AI moves into analysing evidence, structuring opinions or drafting substantive sections of a report, the greater the risk. Questions may then be raised about authorship, independence and compliance with procedural duties.
Experts who choose to use AI should be prepared to explain precisely how it was used and demonstrate that their opinions remain entirely their own.
How can we help?
As the use of AI becomes increasingly common in litigation, expert witnesses must understand both the opportunities and the risks associated with these technologies. Courts continue to emphasise that experts cannot delegate their professional judgement to AI systems and must be able to justify every opinion expressed in their reports.
Bond Solon provides training, which covers all the core skills and knowledge expert witnesses need to fulfil their role in line with their duties and best practice.
We also offer university assessed and certified training programmes that are widely regarded as the industry gold standard by instructing parties.