A July 2023 UK judgment pointed out common factors leading to inherent unreliability of witnesses giving evidence in a commercial case which are worth bearing in mind in all similar situations.

All memory of distant events depends on a process of reconstruction which is inevitably influenced, whether consciously or not, by a multitude of factors. These include: the particular selection of documents from which the witness may be invited to refresh their memory in order to provide a witness statement (some of which may not previously have been seen); the fact that, even if their statement had not been drafted by lawyers, the matters which are included or left out will almost certainly have been dictated by legal strategy; and the fact that preparation for trial may result in the witness becoming increasingly reliant on reconstruction rather than their original experience of the events. There is also a very natural human instinct, when one’s past behaviour is subject to critical scrutiny, to reconstruct events in such a way as to put oneself in the most favourable light possible. This is particularly likely to be the case when the witness has a stake in the outcome of the proceedings through a tie, or loyalty to, or dependence on one of the parties, such as an employer. The court then quoted two paragraphs from a previous case with similarly useful observations, namely:

  1. Memory is especially unreliable when it comes to recalling past beliefs. Our memories of past beliefs are revised to make them more consistent with our present beliefs. Studies have shown that memory is particularly vulnerable to interference and alteration when a person is presented with new information, or suggestions about an event, in circumstances where their  memory of it is already weak due to the passage of time.
  2. The best approach to adopt in a trial of a commercial case is to place little if any reliance at all on witnesses’ recollections of what was said in meetings and conversations and to base factual findings on inferences drawn from the documentary evidence and known or probable facts. This does not mean that oral testimony serves no useful purpose – though its utility is often disproportionate to its length. But its value lies largely in the opportunity which cross-examination affords to subject the documentary record to critical scrutiny and to gauge the personality, motivations and working practices of a witness rather than in testimony of what the witness recalls of a particular conversation and events. It is important above all to avoid the fallacy of supposing that, because a witness has confidence in their own recollection and is honest, evidence based on that recollection provides a reliable guide to the truth.

In the particular case, where some of the witnesses did not impress the court, the court preferred to rely on contemporaneous documents regarding the negotiations and what the court found to be the inherent probabilities of the case.

[World Challenge Expeditions Limited v Zurich Insurance Company Limited [2023] EWHC 1696 (Comm)