The fallibility of human memory and the contemporaneous document “top trump”

In this article, we revisit the changes to the rules on how witness statements should be prepared before turning to look at how judges are rethinking the role of memory and what this may mean for future practice. 

The fallibility of human memory

Psychological research has long provided compelling evidence on the fallibility of human memory and litigators are well versed in the Gestmin approach, drawn from Leggatt J’s judgment in Gestmin v Credit Suisse [2013] EWHC 2560 (Comm) at [22]

“…the best approach for a judge to adopt in the trial of a commercial case is, in my view, 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, as I see it, in the opportunity to 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. 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.” 

The Gestmin decision was followed by the Court of Appeal’s judgment Simetra Global Assets Ltd v Ikon Finance Ltd [2019] 4 WLR 112 who stated at [48]:

“…Indeed, it has become a commonplace of judgments in commercial cases where there is often extensive disclosure to emphasise the importance of the contemporary documents. Although this cannot be regarded as a rule of law, those documents are generally regarded as far more reliable than that the oral evidence of witnesses, still less their demeanour while giving evidence…”

The decisions sparked a wave of changes, culminating in the introduction of Practice Direction 57AC and the new regime for witness statements in the Business and Property Courts. 

Procedural steps for drafting witness statements under PD57AC

To briefly recap, under PD57AC, legal representatives must follow a structured and transparent process when preparing a witness statement in the Business and Property Courts. Key procedural steps include:

1. Initial discussion and explanation:

• The legal representative must explain the purpose and proper content of a witness statement to the witness.
• The witness must understand that the statement should reflect their own recollection, not legal argument or commentary.

2. Document review protocol:

• If the witness is shown documents to refresh their memory, a list of those documents must be included in an appendix to the statement.
• The witness must confirm when they last reviewed those documents and whether they were reviewed before or after the events in question.

3. Drafting in the witness’s own words:

• The statement must be drafted using the witness’s own language and recollection.
• Lawyers may assist in structuring the statement but must avoid paraphrasing or inserting legal interpretations.

4. Avoiding commentary and argument:

• The statement must not include commentary on documents, speculation, or argument.
• It should be limited to facts within the witness’s personal knowledge and recollection.

5. Statement of truth and compliance certificates:

• The witness must sign a Statement of Truth, confirming that the contents are true to the best of their knowledge.
• Both the witness and the legal representative must sign compliance certificates, confirming adherence to PD57AC and the Statement of Best Practice.

Consequences of non-compliance

Failing to comply with these rules can have severe consequences. Courts have the authority to strike out non-compliant witness statements, order re-drafting or impose adverse cost orders. In Blue Manchester Ltd v Bug-Alu Technic GMBH [2021] EWHC 3095 (TCC), the court criticised non-compliant witness statements under PD57AC. While it stopped short of striking them out, it ordered redrafting and emphasised the importance of compliance.

Additionally, courts may impose wasted costs orders on solicitors for improper conduct, including failure to comply with PD57AC. This could expose firms to professional negligence claims.

Impact on litigants in person

PD57AC applies equally to litigants in person (LIPs). LIPs must ensure their statements reflect personal knowledge and avoid using them to argue their case. Courts may strike out non-compliant statements from LIPs and they are not exempt from cost consequences.

The reliability of documents

One of the practical challenges in litigation is the significant time that often passes between the events in question and the drafting of witness statements. Court proceedings can take months or even years to reach trial, meaning witnesses are frequently asked to recall details long after the fact. This delay can further affect the accuracy of their memory, which brings to the fore the status of the contemporaneous document. 

But what about the contemporaneous record of the matter that is directly in issue? Does there remain a case of contemporaneous document “top trump”?

The Popplewell lecture

In his 2023 speech “Judging Truth from Memory: The Science”, Lord Justice Popplewell set out to highlight the issues the fallibility of human memory poses not only for the individual providing evidence-in-chief, but also for the documentary evidence on which so many litigators rely.

There are many graphs available which illustrate how memory can degrade over time and be influenced by various factors such as stress, suggestion and repeated retrieval. Popplewell LJ drew upon the Ebbinghaus forgetting curve from Ebbinghaus’ 19th century study,  which shows that:

• We forget about 50% of new information within an hour of learning it
• After a day, we may retain only 30%
• Without reinforcement, most information is lost within a few days

This demonstrates that it’s only the truly contemporaneous document that we can be confident includes 100% recall of the relevant events. An attendance note made even 60 minutes after the relevant event is likely to exclude 66% of the relevant material. And if, as is often the case with the busy practitioner, it’s not made until the next day, over 72% of relevant material is likely to be missing. 

This, Popplewell LJ made clear, is why there is a risk of the contemporaneous document suffering from exactly the same encoding fallibilities as the human memory itself. 

Cases considering the Popplewell lecture 

The observations of Popplewell LJ were drawn upon in the case of Jaffe v GreyBull Capital LLP [2024] EWHC 2534 (Comm). The case arose from the collapse of Monarch airlines and an alleged misrepresentation of the source of a £165 million capital injection during an October 2016 meeting and subsequent correspondence. In analysing the evidence, Mrs Justice Cockerill DBE considered both the Gestmin and Simetra authorities but also paid attention to the observations of Popplewell LJ:

[230] “However, that is an argument which, as I pointed out in closing, neglects to take into account the possibility (again highlighted by the Popplewell Lecture) of a faulty impression or recollection being encoded at a very early stage and recorded in that document. 

[231] Ultimately therefore the document can be taken as the basis for a compelling argument; but it itself must be tested against the facts in the full context. That context includes considering what was common to both parties in terms of knowledge , but also what (if anything) the parties were each focussing on which did not get communicated to the other side, which might affect both encoding and recording or which might affect how Mr Meyohas expressed himself”

Having undertaken that analysis, Cockerill J came to the conclusion that the contemporaneous document was “in the critical respect (entirely innocently) inaccurate”.  

The Jaffe decision serves as a useful reminder of the importance of challenging both witness evidence and contemporaneous documents and the danger of assuming that simply because a record can be found, that record will be accepted. It also suggests a movement by the judiciary away from the strict Gestmin/Simetra approach and towards the more nuanced views expressed in the Popplewell lecture. 

This is demonstrated by more recent cases such as GI Globinvestment Ltd v XY ERS UK Ltd [2025] EWHC 740 (Comm) where a similar approach was taken to evidence in the context of allegations of deceit and conspiracy. Jacobs J’s judgment includes a helpful review of the Popplewell lecture and the case law about the assessment of evidence. Burdett v Burdett [2025] EWHC 480 (Ch) also refers to the Popplewell lecture in the context of evidence given in an inter-family business dispute.

Conclusion

The evolving understanding of how unreliable memory can be (and the judiciary's growing awareness of this issue) underscores the importance of following best practices when preparing witness statements, as well as the need for practitioners to be wary of slipping into the trap of assuming the contemporaneous document is infallible. We should expect far greater scrutiny from the court and approach discussions with opponents prepared to challenge (and be challenged on) the real strength of both the witness testimony and the contemporaneous record.