What percent of plea bargains are in exchange for testimony?

Answer 1

Legally?

None. It is illegal for a prosecutor to offer a straight "quid pro quo" of "If you testify against Joe we will give you a better deal".

If a witness is told, or even led to believe, that his testimony against a third party will result in his charges being reduced, or that it will be taken into account at sentencing, then the law requires that the DA tell that to the defense, and that the jury be advised, when the witness testifies, that he has an incentive to do so.

In the "real world" however, DA's DO offer such deals, pussyfoot around them as they will, and the sometimes DO neglect to tell the defense about them. This leads to reversals from time to time when a jailhouse snitch is found to have been released shortly after giving testimony in someone else's case.

Richard