It’s often said that Judges hate witnesses and love documents. Unless tampered with, a document is a permanent and faithful record of its content. Even the most well-intentioned witnesses can be tripped up at trial by something they or others have recorded in a document during or shortly after an event. We all know that memory fails and it is the function of the trial process to attempt to remedy this failure. But the process by which courts actually go about separating reality from fiction is rarely the subject of detailed judicial comment. The judgment of Leggatt J in Gestmin v Credit Suisse and another  EWHC 3560 (Comm) is therefore worth reading.
This case concerned alleged negligent investment advice relating to the sale and purchase of shares. Under the section “Evidence based on recollection” Leggatt J argues that the legal system has not ‘sufficiently absorbed the lessons of a century of psychological research into the nature of memory and the unreliability of eyewitness testimony’. That research suggests that we fall into error in supposing ‘(1) that the stronger and more vivid is our feeling or experience of recollection, the more likely the recollection is to be accurate; and (2) that the more confident another person is in their recollection, the more likely their recollection is to be accurate.’
He also explains how people think of their memories as fixed at the time of the experience, which then fades with time, whereas research has demonstrated that memories are “fluid and malleable” and are “constantly rewritten whenever they are retrieved”. External information intrude into the memory, as well as the witness’s own thoughts and beliefs. Both of these factors can dramatically change the memory.
Leggatt J cites research that suggests a memory can be rewritten when a person is presented with new information or suggestions about an event, particularly when the event happened some time earlier (he refers to this as being “particularly vulnerable to interference and alteration”). The process of civil litigation can itself subject the memories of witnesses to powerful biases. In particular a witness:
(1) May have a stake in a particular version of events.
(2) May have a “desire to assist, or at least not to prejudice” the case of the party calling them as a witness.
(3) Will be asked to make a statement long after the events took place and, usually, that statement will be drafted for them by a lawyer who is aware of the importance of the witness’s evidence to the issues in the case. The statement is likely to go through several versions before being finalised
(4) Will “refresh” their memory from documents, which may not be limited to contemporaneous documents, but also include the parties’ statements of case. The effect of this is “…to cause the witness’s memory of events to be based increasingly on this material and later interpretations of it rather than on the original experience of the events.”
The effect of these “powerful biases”, Leggatt J concludes, is such that the court may be best served by placing ‘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.” He goes on, the value of oral evidence lies 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 particular conversations and events.’
This judgment is a clear reminder (as if one was needed) of the importance of advising clients to create and keep detailed, contemporaneous records of meetings and conversations that could foreseeably end up in litigation. And where an event is completely unsupported by documentation, the period within which signed witness evidence can be produced may be crucial.