Criminal prosecutors understand the importance of cooperating witness to the criminal justice system.  Cooperating witnesses are vital to the criminal justice system because they are in the unique position of explaining to a jury the operation of a criminal enterprise.  Without insider information, there are numerous criminals and criminal organizations that would never have been dismantled and punished.  As we have seen in the recent Manafort prosecution, cooperating witnesses have to be carefully used by prosecutors and can cause harm to the criminal prosecution.

Rick Gates testified during the Manafort case and apparently many of the jurors had difficulty believing his testimony.  That is not unusual.  A prosecutor has to carefully prepare a cooperating witness and sometimes a cooperating witness veers off and makes comments or gives answers that are not helpful.  Prosecutors all fear a cooperating witness meltdown – a cooperating witness who admits conduct not known to the prosecutor in prior debriefings or when the cooperator witness fails to answer questions carefully.

Juries view cooperating witnesses with great suspicion.  In the District of Columbia, cooperating witnesses when used in gang or street crime cases have a strong record of success.  Some jurors told me they believed them more than the police witnesses.  In white collar cases, cooperating witnesses are viewed suspiciously.  The one danger that a prosecutor has to avoid is making a case dependent on the testimony of a cooperating witness.  In the absence of corroborating evidence, a criminal case can go down in flames when it rests exclusively on the shoulders of a cooperating witness.

In many cases, the character and personality of the cooperating witness can make the difference.  The dynamic can change depending on how a prosecutor presents a cooperating witness or how the defense attorney cross-examines a cooperating witness.  Jurors usually have a visceral reaction to someone who is testifying in the hopes of a lenient sentence.  Prosecutors have to be acutely aware of these issues, present the cooperating witness honestly and fairly, and embrace the positive and negative aspects of the cooperating witness.

In general, prosecutors want to ensure that a cooperating witness is required to plead guilty to the crimes they committed and not be given any breaks up front.  By doing so, the cooperating witness is looking at the same penalty as the defendants against whom he or she is testifying.  The only difference should be the cooperating witness’ commitment to cooperate and tell the truth.  The benefit to the cooperating witness will be ultimately dispensed by the trial judge in front of whom he or she testifies.

The prosecutor has to make sure the cooperating witness explains this arrangement carefully.  In today’s sentencing world without mandatory guideline sentences, most cooperating witnesses do not face a mandatory sentence (except drug mandatory minimums).  Therefore, the judge has more discretion than in the past to provide a sentencing reduction.

Jurors also tend to favor criminal cases where more than one cooperating witness testifies for the government.  In the Manafort case, the prosecutors put on one cooperating witness (I am not including the witnesses who insisted on immunity because of 5^th Amendment issues), Rick Gates, and his performance ultimately hurt the government.  By contrast, if the government presented multiple cooperating witnesses, I am sure jurors would have been more likely to credit a cooperating witness.

There is no question that a cooperating witness, like a defendant who testifies, has a lot at stake and may not necessarily tell the truth.  It is the prosecutor’s job, however, to review the cooperator’s testimony, to ensure that it comports with the evidence in the case, and guard against any exaggerations or fabrications.  Prosecutors cannot shirk this responsibility.