In what circumstances will a prosecutor be permitted to use a defendant's statement at trial in breach of a prosecutor's promise not to do so?

In light of the foregoing decisions of the high court, we conclude that it was fundamentally unfair and a violation of due process for the prosecutor in this case to use at trial defendant's July 21, 1987, statement in breach of the prosecutor's promise not to do so. Just as the defendant in Santobello v. New York, supra, 404 U.S. 257, 92 S.Ct. 495, waived his constitutional rights and pleaded guilty in exchange for and in reliance upon the prosecutor's promises in the plea agreement, defendant here waived his constitutional right to remain silent in exchange for and in reliance upon the prosecutor's promise not to use in court anything defendant said. Because the prosecutor's promise induced defendant's waiver of his constitutional right to remain silent, due process required that the prosecution honor the promise. As is true of a guilty plea, when a defendant's waiver of the right to remain silent "rests in any significant degree on a promise or agreement of the prosecutor, so that it can be said to be part of the inducement or consideration, such promise must be fulfilled." (Santobello v. New York, supra, 404 U.S. at p. 262, 92 S.Ct. at p. 499.)