In 2006, US Federal prosecutor, Carla Martin, was accused of “witness tampering” in the trial of convicted 911 terrorist, Zacarias Moussaoui. It was said that she:

  • emailed copies of trial transcripts to witnesses, with instructions on how they should testify (directly contravening a court order)
  • prepared witnesses together, rather than apart
  • prevented witnesses from speaking to the defence

Martin received widespread opprobrium from the legal profession. But was her biggest blunder in being caught? And was there just a hint of humbug in her critics’ umbrage? Former public defender, David Feige, seemed to think so. In an article for The Slate at the time, Tamper Proof, he pointed out:

There is no question that this sort of behavior violates the spirit of fairness that is supposed to guide our criminal-justice system. There is also no question that what Martin did happens all the time—just not via e-mail.

Witness-coaching isn’t just commonplace, it’s endemic. Every single day, in state and federal courts across the country, prosecutors and defense lawyers summon their witnesses and coach (most would prefer the term “prepare”) their testimony. This preparation is not only permissible but important, and it routinely includes a discussion of the questions to be asked, and even helpful hints on improving the testimony. It is not at all uncommon to prod a witness’s memory, dredging up old police reports, grand jury testimony, or prior conversations to get a witness to say what a prosecutor wants them to say, and in the way a prosecutor believes will be most effective. In the dozens of prosecutorial prep sessions I’ve witnessed over the years, I’ve seen prosecutors threaten, cajole, and remind witnesses in no uncertain terms of what they want said on the stand, often by referring to other evidence in the case and even the statements of other witnesses. “Don’t worry about it, I have X to say Y” is as common a refrain in these sessions as, “What happened next?”

Strictly speaking, witness coaching is prohibited in the US just as it is elsewhere. In this context, coaching means “conduct by a lawyer that alters a witness’ story about the events in question”.[i] As New York jurist, Judge Francis Finch put it back in 1880:[ii]

While a discreet and prudent attorney may very properly ascertain from witnesses in advance of the trial what they in fact do know and the extent and limitations of their memory, as guide for his own examinations, he has no right legal or moral, to go further. His duty is to extract the facts from the witness, not to pour them into him; to learn what the witness does know, not to teach him what he ought to know.

Tensions arise because, in the US, it is also considered to be both an ethical and professional duty for prosecutors to “prep” (as it is called) witnesses.[iii] It is expected that even criminal prosecutors will interview witnesses at an early stage, later help the witness to refresh his or her memory and challenge any inconsistencies or conflicts in the evidence; it is also commonplace to rehearse the witness’ testimony, through role play or other means. This command-control approach to  witness prepping gives rise to countervailing ethical misgivings and has even led one commentator to suggest that witness coaching is the “dark, dirty secret” of the US adversary system.[iv]

If nothing else, the absence of bright line tests to establish when lines have been crossed gives cause for concern. Brittany Cohen has been critical of the standards followed by the courts which “prohibit only the most egregious conduct, such as directing witnesses to give perjured testimony or providing witness testimony that the prosecutor knows to be perjured”.[v] Cohen points out that even when detected, there is little in the way of remedy; the perception being that cross examination is a sufficient safeguard.[vi]

However, again according to David Feige in Tamper Proof, the very practice of witness prepping renders cross examination an inadequate defence:

What guides such coaching sessions is not some abstract ideal of the independent witness, but rather the question of how any coaching could play later, on cross-examination. A good prep session, in other words, will effectively shape a witness’s testimony to maximize its impact while minimizing the danger that cross-examination will pull back the curtain on what is actually happening. You coach just well enough to diminish the appearance of coaching.

Seen in this light, witness preparation in the US seems less about eliciting the best evidence, and more about mastery of a dark art.

This is the first of a series of posts on witness preparation. In Part 2 we will contrast the style of witness preparation in the US with the rules and practice in the UK.


[i] Richard C Wydick The Ethics of Witness Coaching 17 Cardozo L. Rev. 1

[ii] Re Eldridge 82 N.Y. 161 (N.Y. 1880); a bygone era when, it appears, only men were qualified to be either lawyers or witnesses.

[iii] Brittany R Cohen Whose Line is it Anyway?: Reducing Witness Coaching by Prosecutors 18 N.Y.U. J. Legisl. & Pub. Policy 985 (2015) at pp 989 and 1009, citing Nixon v United States, 703 F. Supp. 538, 563 (SD Miss, 1988); State v Earp, 571, A.2d 1227, 1234 (md.1990)

[iv] Bennett L. Gershman Witness Coaching by Prosecutors –23 Cardozo L. Rev. 829 (2001-2002)

[v] Cohen (Note 3) at p 1011

[vi] Cohen (Note 3) at p 1013