ASSESSING WITNESS CREDIBILITY: A REMINDER OF THE BASIC PRINCIPLES
Today is is a good day to look again at the judgment of Mr Justice Leggatt in Gestmin SGPS S.A. -v- Credit Suisse  EWCA 3560 (Comm). This is case that is now mentioned regularly in cases involving witness recollection and dispute of facts.
WHY LOOK AT GESTMIN?
In Gestmin Leggatt J spent some time setting out principles relating to the assessment of witness evidence. These principles have been adopted in numerous cases since. It is probable that they are (consciously or unconsciously) adopted by most judges who determine issues of fact. This blog has examined the case before. However I want to go through the relevant matters point by point. This is definitely not wasted time
This ability to assess witness evidence is an important part of a litigator’s task. It is a skill not taught, and rarely written about. Just looking at this one judgment in detail gives an important insight into how witness evidence will be assessed.
POINT BY POINT
- There obvious difficulty with allegations and oral evidence based on recollection of events which occurred several years ago is human memory.
HUMAN MEMORY IS FALLIBLE
- Everyone knows human memory is fallible.
- The legal system has not sufficiently absorbed the research into the nature of memory and the unreliability of eyewitness testimony.
- We are not aware of the extent to which our own memories are unreliable and believe our memories to be more faithful than they are.
COMMON MISCONCEPTIONS WITH MEMORY
Two common and related errors are that:
- The stronger and more vivid is our feeling or experience of recollection the more likely the recollection is to be accurate.
- The more confident another person is in their recollection, the more likely their recollection is to be accurate.
THE FAULTY MODEL OF MEMORY AS A MENTAL RECORD
Underlying both these errors is a faulty model of memory as a mental record which is fixed at the time of the event and fades over time.
- Memories are fluid and malleable.
- They are constantly rewritten whenever they are retrieved.
- This is true of “flashbulb” memories of a shocking or traumatic event.
- The very description “flashbulb” memories is misleading because it reflects the misconception that memory is like a camera.
- External information can intrude into a witness’s memory as can their own thoughts and beliefs.
- This can cause dramatic changes in recollection.
- Events can be recalled as memories which did not happen at all or which happened to someone else (“a failure of a source of memory”.
MEMORY IS ESPECIALLY UNRELIABLE WHEN IT COMES TO RECALLING PAST BELIEFS
Memory is unreliable when it comes to past beliefs.
- Memories are revised to make them more consistent with our present beliefs.
- Studies show that memory is particularly vulnerable to inference and alteration when a person is presented with new information or suggestions when their memory is already weak due to passage of time.
THE PROCESS OF CIVIL LITIGATION ITSELF SUBJECTS MEMORY TO BIASES
The process of civil litigation itself subjects the memories of witnesses to powerful biases.
- Witnesses have a stake in a particular version of events.
- This is more obvious in relation to parties and those with ties of loyalty to parties.
- More subtle influences include the very process of making a witness statement and going to court to give evidence.
- A desire to assist the party calling a witness and a natural desire to make a good impression can be significant motivating factors.
THE PROCEDURE OF PREPARING FOR TRIAL HAS A CONSIDERABLE INTERFERENCE WITH MEMORY
Considerable interference with memory is introduced by the process of preparing for trial.
- A witness is often asked to make a statement a long time after the relevant events.
- The statement is usually drafted by a lawyer who is lawyer who is conscious of the significance of the issues in the case.
- The statement is made after a witness’s memory has been “refreshed” by reading documents.
- The documents include pleadings and other argumentative material which the witness did not see at the time or which came into existence after the event.
- The statement goes through several versions before it is finalised.
- Months later the witness is asked to re-read the statement and documents before giving evidence in court.
- The effect of this is to establish in the mind of the witness the matters in the statement and documents whether they be true or false.
- This also causes the witness’s memory to be based increasingly on the material and later interpretations rather than the original events.
THE DIFFERENCE BETWEEN RECONSTRUCTION AND RECOLLECTION
Witnesses are often asked in cross-examination the difference between reconstruction and recollection.
- These questions are misguided.
- There is a presumption that there is a clear distinction between recollection and reconstruction.
- All remembering of distant events involves reconstruction processes.
- Such questions disregard the fact that such processes are largely unconscious and that the strength, vividness and apparent authenticity of memories is not a reliable measure of their truth.
THE APPROACH OF THE JUDGE
Mr Justice Legatt was particularly concerned with commercial cases. However, again, these matters are probably universal.
- A judge places little, if any, reliance on witnesses’ recollections of what was said in meeting and conversations.
- Factual findings are based on inferences drawn from the documentary evidence and known probable facts.
THIS DOES NOT MEAN THAT ORAL EVIDENCE SERVES NO USEFUL PURPOSE
- The utility of witness evidence is often disproportionate to its length.
- Its value largely 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 what the witness recalls of particulars conversations and events.
THE KEY POINT
- “Above all, it is important to avoid the fallacy of supposing that, because a witness has confidence in his or her recollection and is honest, evidence based on that recollection provides any reliable guide to the truth.”