The High Court decision in Ebanks-Blake v Calder provides an important clarification on the proper separation between factual and expert evidence in medico-legal claims.

Contrary to a common assumption in litigation preparation, the case does not support aligning factual witness evidence with expert opinion. Instead, it highlights the serious risks when factual evidence is influenced by expert views.

The judgment serves as a clear warning: factual witness statements must stand on their own foundation, rooted in contemporaneous records and the witness’s own recollection, and must not be shaped by expert analysis.

The primacy of independent factual evidence

Factual witness evidence has a distinct and limited role. It is concerned with what happened, not why it happened or whether it met a clinical standard.

The court emphasised that a factual witness statement, particularly from a defendant clinician, should be based on the witness’s own memory, contemporaneous clinical records and what was known and done at the time. It should not be adjusted, refined, or reframed after reviewing expert evidence.

This distinction is fundamental. Once a factual account is influenced by expert opinion, it risks losing its evidential integrity.

The danger of expert-influenced witness evidence

A central issue identified by the judge was that the defendant doctor’s witness statement and trial evidence had been influenced by expert opinion obtained on his behalf.

This was improper.

Factual evidence must not be reconstructed to align with an expert’s theory. Nor should it be supplemented with reasoning derived from expert reports. It is also inappropriate for a witness statement to be altered to better support a defence after expert review.

When this occurs, the evidence ceases to be purely factual. It becomes a hybrid of fact and opinion, which the court is likely to treat with caution.

The risk is not just technical, it is evidential. The court, as a consequence, may give reduced weight to the witness’s evidence, prefer contemporaneous records over reconstructed accounts and question the reliability of the witness entirely.

Why independence matters

The integrity of factual evidence lies in its authenticity.

Even where a witness’s recollection is imperfect, the court expects it to reflect what the witness actually remembers and what was actually recorded at the time. Not what, in hindsight, would have been logical or defensible.

Allowing expert opinion to shape factual evidence introduces hindsight bias and undermines the court’s ability to distinguish between what actually occurred and what is now said to have occurred in light of expert critique.

The correct relationship between factual and expert evidence

The case reinforces a strict boundary, that factual witnesses provide the narrative of events and that experts interpret those events and offer opinion. The flow of influence must be one-directional.

Experts consider the factual evidence and therefore factual witnesses must not adapt their evidence based on expert views. Any reversal of this relationship compromises the fairness of the process.

Practical implications for medico-legal practitioners

The judgment has clear practical consequences. Firstly, witness statements must be drafted early and independently.  They should be prepared before exposure to expert reports wherever possible. Secondly, contemporaneous records remain the most reliable evidence and should form the backbone of any statement. Thirdly, witnesses should not justify, analyse, or rationalise their actions. Next, factual accounts should not be revised by experts. Once a statement is influenced by expert opinion, its evidential value may be undermined. Lastly, legal teams must ensure that factual and expert evidence remain clearly separated.

Judicial approach to compromised evidence

Courts are highly sensitive to any blurring of roles.

Where a factual witness appears to have adopted expert reasoning, the court may:

• Treat the evidence as unreliable
• Prefer contemporaneous documentation
• Discount parts of the testimony altogether

This applies equally whether the influence is explicit or subtle.

Conclusion

Ebanks-Blake v Calder is not a case about improving factual evidence through expert input. It is the opposite. It is a reminder that factual witness evidence must remain independent, unfiltered, and grounded in the witness’s own knowledge and records.

The strength of medico-legal evidence lies not in alignment, but in clear separation of roles. When that boundary is respected, the court can properly evaluate both fact and opinion. When it is not, the credibility of the evidence (and potentially the outcome of the case) is put at risk.