Source of the following article Persuasive Litigator.

By Dr. Ken Broda-Bahm: 


The way trial and deposition testimony works is that you hear from one witness at a time. We have individual testimony, we don’t have group testimony. Or do we? Is there a chance that when we are hearing from the individual, we are hearing a message that has already been formed and filtered in reference to a group’s perceptions and opinions? New research shows that the answer might be, “Yes.” Based on a release from the University of Huddersfield carried in ScienceDailyDara Mojtahedi, a lecturer in forensic psychology, finds support for a phenomena he calls, “co-witness familiarity on statement similarity.” What that means is that we are influenced, sometimes decisively, by our reference groups, and that influence leaks into testimony. “It is human nature to give added credence to the views of family and friends,” he writes, “but this could lead to inaccurate eyewitness statements in court cases.”

The research focuses on the reliability of eyewitness testimony, something that tends to matter more in criminal than civil cases, but one can easily see how the implications apply to witness testimony in general. Mojtahedi took 420 participants and formed them into groups including people who had known each other for three months or more. The participants then watched a video showing a real-life fight breaking out. Then they either gave individual accounts on who was to blame, or they were allowed to confer before giving accounts. The findings showed that the discussions after the event significantly increased the similarity of the resulting accounts. In other words, after conferring, the witnesses were on the same page, sometimes in inaccurate ways. Reporting research showing that in actual trials, eye witnesses know each other around 85 percent of the time, Mojtahedi reasons that this familiarity leads to less skepticism and greater confidence, which in turn allows incorrect perceptions to be repeated and magnified. In this post, I will take a look at what this effect has to say about witness examination and witness preparation. 

There are a few implications to the finding that our reference groups color our testimony. 

Lock Down the Critical Memories

Within your own  witness pool, it is important to make sure that the group knows not to have substantive conversations about the case without counsel present. One additional step can help to protect the witness from the cross-contaminating effects that can come from time and from conversations with the attorneys and their own preparation sessions. That step is to write a memo recording all of your recollections as early as possible, before they’ve had a chance to get mixed in with the recollections of others. Ensure the witnesses address that memo to counsel, so it is protected, but keep it with their records to make sure they aren’t drifting away from their earliest and best recollections. 

Keep the Preparation Sessions Solitary

As a general rule of thumb, prepare one witness at a time. The only ones in the room should be the attorney, the witness, and a trial consultant if you’re using one. The only time it makes sense to make an exception to this rule would be when you are hosting a session for several witnesses focusing on the general principles of testimony. In those cases, however, it is important to make sure that you are just focused on principles, and not focused on the facts of the case at hand. While you might think it is a good idea to ‘get everyone on the same page,’ a joint session focusing on the actual facts of testimony carries too much risk. If the conversations shift people’s perceptions, even a little bit (and the research suggests it does), then the resulting mix of perceptions will leave your witnesses vulnerable in cross-examination. 

Ask About Conversations in Discovery

Of course, it is already common to ask near the beginning of a deposition, “What discussions have you had about this case?” but this research provides the reminder that it is particularly important to focus on those with whom the witness is close. Mojtahedi notes, “A big question that police officers, lawyers and indeed jurors should be asking is, did you witness this incident with friends or did you witness it with strangers?” If they were with friends, or others who they have known for some time, then the chances that the subject would have come up seems high. Of course, there’s no guarantee you’ll get a complete and honest answer. But if you ask, you might get lucky and uncover an opportunity to show that the witness’s recollections have been influenced by these conversations. 

Remember that it Applies to Your Own Team

The self-referencing construction of evaluations and memories doesn’t just affect groups of witnesses, it affects all teams, and that includes the team of lawyers, paralegals, experts, and consultants who are helping to try your case. Group-think within that context can make some perceptions and opinions seem like common sense, and lead them to go unchecked. To guard against that, make sure that you are building a team that is diverse and a culture where it is okay to dispute and to disagree within the team.  


Other Posts on Witness Influence: 


Image credit:, used under license