Part 1 of this article examined how witnesses may be influenced before and during a police investigation through discussions with other witnesses, family members, social media, news coverage, suggestive questioning and translation. The risk of contamination, however, does not end when the police obtain a witness statement. It may continue when prosecutors meet witnesses to prepare for trial and even after a witness begins giving evidence in court.

Prosecutors and counsel for the accused typically confer with witnesses before trial, called a witness conference. They need to understand what each witness knows, assess the strength of the evidence, prepare the witness for court and identify inconsistencies that may arise during cross-examination. Yet this necessary preparation carries a risk which is that the line between helping a witness give clear and truthful evidence and influencing the substance of that evidence can become blurred.

What should a prosecutor or a defense attorney do when a witness’s present recollection differs from the statement originally given to the police? Can they draw the witness’s attention to the earlier account? What if reviewing that statement changes the witness’s memory? What if the earlier statement was false and the later account is true? Particularly for prosecutors, should the new account affect the decision to continue the prosecution? This second part examines these questions, the ethical boundary between witness preparation and witness coaching, and the restrictions that apply once a witness has begun giving evidence in court.

Prosecutors Preparing for Trial

When prosecutors prepare for trial, they hold conferences with prosecution witnesses in anticipation of their courtroom testimony. During a witness conference, ethical rules require the prosecutor to avoid influencing the witness to say anything other than what the witness independently observed or remembers. Three important factors must be addressed at this stage.

The first, and simpler, consideration is that witnesses should be interviewed separately. The prosecutor should ensure that each witness gives an account away from the hearing of the others and should caution them against comparing accounts. A prosecutor must not allow prosecution witnesses to align their accounts to form a coherent story that fits the facts of the charge. More importantly, the prosecution must not allow witnesses to manufacture corroboration of each other’s accounts.

Rules 54 and 82 of Ghana’s Legal Profession (Professional Conduct and Etiquette) Rules, 2020 (L.I. 2423) prohibit coaching a witness or encouraging evidence that is untruthful or incomplete. They provide:

Integrity of evidence

54. (1) A lawyer shall not advise or suggest to a witness to give false evidence.

(2) A lawyer shall not

(a) suggest, or

(b) condone a client or another person suggesting to a prospective witness, the content of any particular evidence which the witness should give at any stage in a proceeding.

Contact with a witness

82. A lawyer shall not

(a) coach a witness in relation to the evidence of the witness;

(b) encourage a witness to give evidence which is untruthful or which is not the whole truth.

The second and third factors concern witness memory and the preparation of witness statements for court. Prosecutors often do not engage directly with witnesses until a case is approaching trial. During docket review, they rely largely on investigative reports and statements taken by the police to determine whether the available evidence supports a charge. After charges have been filed and the case has been scheduled, prosecutors invite witnesses to conferences and prepare the witness statements required for case management.

Under the 2018 Practice Direction on Disclosures and Case Management in Criminal Proceedings, a witness statement may, subject to the agreement of the parties, be tendered as the witness’s evidence-in-chief. Whether the statement is adopted or the witness gives oral evidence-in-chief, the defence may use material contradictions between the filed witness statement and an earlier police statement to challenge the witness’s credibility. This is where two complexity begins.

A: When a Witness’s Account Changes

A witness may attend the prosecutor’s conference with a story substantially different from what they initially told the police. Is it ethical for the prosecutor to say, “But in your statement to the police, you said something different”? Is a prosecutor obliged to remind the witness of the first account?

Ghana’s ethical rules permit a lawyer to identify and examine such differences in the testimony. Rule 54 of L.I. 2423 states:

Integrity of evidence

(3) Subrules (1) and (2) do not apply where the lawyer (NB: subrules stated above)

(a) expresses a general admonition to tell the truth;

(b) questions and tests in conference the version of evidence to be given by the prospective witness; or

(c) draws the attention of a witness to an inconsistency or difficulty with evidence given by that witness.

(4) Despite paragraph (c) of subrule (3), a lawyer shall not coach or encourage a witness to give evidence which that witness believes to be false.

The rule therefore distinguishes between legitimate testing of evidence and coaching witnesses. A prosecutor may ask a witness to explain why a new account differs from an earlier one. The prosecutor may not insist that the witness should adopt whichever version better supports the prosecution.

In addition, Ghana’s Evidence Act, 1975 (NRCD 323) anticipates in section 77 that witnesses may need to refresh their memories in court in respect of their testimonies. It follows that a witness may be permitted to review an earlier statement for the purpose of refreshing their memory. However, the sequence matters. To reduce the risk of suggestion, the prosecutor should first obtain the witness’s present account using open-ended and non-leading questions. Only after that account has been recorded should the prosecutor identify a discrepancy and invite the witness to explain it. Showing the earlier statement too soon may itself influence what the witness later believes they remember. A useful sequence would be to:

1. Ask the witness to give an uninterrupted account.
2. Note any material difference from the police statement.
3. Ask neutral questions about the reason for the difference.
4. Where needed, allow the witness to read the earlier statement.
5. Record whether the witness maintains, modifies or rejects either version.

A prosecutor who encounters a substantial difference should preserve both accounts and record the explanation provided by the witness. The prosecutor should not insist that the witness adhere to one account or the other. Where necessary, the prosecutor may ask the investigator to take an additional or supplementary statement. The new statement should not replace or conceal the earlier account. Both must be preserved and disclosed to the defence in accordance with the prosecution’s disclosure obligations, and any statement on which the prosecution intends to rely must be filed and served on the defence as part of disclosures. If the timing or circumstances of the new statement are challenged at trial, the prosecutor should be able to explain transparently how and why it was obtained. The judge or jury must ultimately determine what weight to place on the testimony.

B: Preparing Court Witness Statements

The final and most complex situation, which requires institutional attention, concerns the preparation and use of court witness statements. I once observed a case in which counsel for the accused argued that a witness statement typed by the prosecution but signed by the witness could not truly be said to have been prepared by the witness. Counsel further argued that the prosecutor had selected language specifically designed to prove the elements of the offence. In other words, the prosecutor’s wording may have contaminated what was eventually presented as the witness’s evidence-in-chief. For example, a prosecutor who understands the elements of murder may draft the following sentence: “I saw the accused stabbing the deceased.” Yet the witness may initially have said only: “I saw him doing it.”

The prosecutor’s version is clearer, but it does more than may be allowed in advocacy. It identifies “him” as the accused and defines “doing it” as stabbing. None of those details should be supplied by the prosecutor. The prosecutor is entitled to ask what the witness means by “doing it.” Indeed, clarification is essential. The appropriate follow up question should be, “What exactly did you see him do?” rather than, “Do you mean that you saw the accused stab the deceased?” The first invites the witness to clarify their own account; the second introduces the fact that the prosecution needs the witness to prove.

The thing is, a witness’s signature signifies their adoption of the statement, but it does not by itself establish that every word or detail came from that witness. On the other hand, the fact that a prosecutor types or structures a statement does not also necessarily mean that the statement is no longer that of the witness. The critical issue is whether its factual content came from the witness’s own recollection. In preparing a court witness statement, prosecutors should therefore:

1. Read the witness statement and be familiar with the testimony before the conference begins.
2. Obtain the witness’s uninterrupted account before drafting and check against their earlier statement.
3. Use open-ended questions especially when asking important or disputed facts.
4. Preserve the witness’s own expressions where their wording is significant.
5. Distinguish personal observation from information received from other people.
6. Avoid legal conclusions and language designed merely to align with the elements of the offence.
7. Use jurats to record the language in which the account was given and the use of an interpreter, where applicable.
8. Read the completed statement back to the witness in a language the witness understands.
9. Invite corrections without pressuring the witness to add details.
10. Preserve earlier statements and document every material change in anticipation for cross-examination.

These safeguards allow the prosecutor to present a clear and organized statement without turning the prosecutor’s theory of the case into the witness’s supposed recollection.

Reconsidering the Charge

A significantly changed account must also prompt the prosecutor to reconsider the strength of the case. Witness preparation is not simply a process of preparing witnesses to support a charging decision that has already been made. If the conference reveals that an essential witness is unreliable, has withdrawn a material allegation or can no longer provide evidence establishing an element of the offence, the prosecutor must review whether the charge remains sustainable.

Depending on the circumstances, the prosecutor may request further investigation, to make sure the witness has not been threatened, intimidated or bribed to change their story. Based on the outcome of their investigations, the prosecutor may choose to amend the charge where legally permissible, proceed on other independent evidence, decline to call the witness, treat the witness as a hostile witness, or discontinue the prosecution through the appropriate procedure. This way, the prosecutor maintains their obligation is to seek justice within ethical and legal boundaries.

Witness Contamination in Court

At trial, witnesses who have not yet testified may be excluded from the courtroom so that they do not hear or see the testimony of other witnesses. Section 78 of the Evidence Act authorizes the court to exclude witnesses and take appropriate steps to prevent communication between witnesses awaiting examination. This helps preserve the independence of their accounts and prevents them from preparing answers based on evidence already given. The section reads:

(1) The court, on its own motion or at the request of a party, may exclude from the courtroom any witness so that he cannot hear or see the testimony of other witnesses.

(2) The court, on its own motion or at the request of a party, may during any trial take such steps as it considers necessary and proper for preventing communication with or between witnesses who are within the court house or its precincts awaiting examination.

Where a witness has begun but not completed their testimony, courts commonly warn the witness not to discuss the case with other witnesses or persons involved in the proceedings until the witness has been discharged. L.I. 2423 extends the communication restriction to lawyers on both sides:

Contact with a witness

82. A lawyer shall not

(c) communicate directly or indirectly about a case with a witness, once that witness has begun to give evidence and until the evidence of that witness has been concluded, except with the consent of the representative of the opposing party or of the Court.

This prohibition is important during breaks and adjournments. After observing the omissions, contradictions or admissions from a witness’s testimony, a lawyer may be tempted to explain a question, remind the witness of an earlier statement or help the witness repair a weakness before testimony resumes at the next sitting. Even where the intention is to clarify the truth, such an intervention may affect the independence and integrity of the evidence.

Rule 82 must, however, be read alongside Rule 72, which contains more detailed provisions governing communication with a witness who is giving evidence. Rule 72 permits limited communication in specified circumstances but prohibits discussion of the evidence at particularly sensitive stages, including during cross-examination and between cross-examination and re-examination. Where there is any uncertainty, counsel should seek the court’s permission before communicating with the witness about the case. The full text of L.I. 2423 can be accessed here.

What happens outside the courtroom is more difficult to control. A court warning provides important notice, but it cannot always physically prevent communication outside the courtroom. Witnesses and lawyers must therefore understand that the restriction continues throughout breaks and adjournments until the witness’s evidence has concluded.

Why Witness Contamination Matters

Witness contamination creates several challenges for the criminal justice system.

• It can distort the truth. The primary objective of an investigation is to determine what happened. Contaminated memories may move investigators further away from the truth rather than closer to it.
• It can strengthen incorrect information. When several witnesses provide the same incorrect detail, that detail may appear more reliable than it is. Investigators, lawyers, jurors and judges may be impressed by apparent consistency without realizing that the consistency resulted from contamination rather than independent corroboration.
• It can affect fair trials. Accused persons are entitled to a fair trial. Where witness evidence has been influenced by outside information, the reliability of that evidence may be compromised.
• It can affect victims and witnesses. Witness contamination does not affect only accused persons. Victims and other genuine witnesses may also experience frustration when they are confronted during cross-examination with inconsistencies arising from altered memories.

Does Witness Contamination Mean the Witness Is Lying?

No. This is one of the most important points to understand. Witness contamination is fundamentally different from deliberate dishonesty which may result in a perjury charge. A contaminated witness may be honest and cooperative. The problem is that memory can be influenced without the witness realizing it.

Lawyers who call witnesses, especially prosecutors, must make witnesses aware of the risk of contamination. To build rigorous criminal cases, prosecutors should prioritize early witness conferencing and remain willing to reconsider charges where they encounter unreliable testimony.

Opposing counsel may test a witness’s account through cross-examination. In practice, a lawyer may confront a witness with an account given by another witness. Some witnesses maintain their original account while others change it. The court must then evaluate the reliability of the testimony, bearing in mind that an honest witness can still be mistaken.

Conclusion

Witness contamination is an often-overlooked challenge within the criminal justice system yet it has serious consequences for fairness and justice. Investigators, lawyers, courts and witnesses must therefore be alert to these risks and remain mindful of how testimony is obtained, prepared and presented. Preventing contamination is an important safeguard in the search for truth, particularly when another person’s liberty is at stake.

Acknowledgement: I am grateful to Christabel Selma Anafure Esq. for her insights on witness contamination through her observations in court. That insight inspired me to examine the subject more closely and ultimately led to this two-part series.

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