In Wainwright v. Greenfield (1986) 474 U.S. 284, the prosecution introduced evidence that when given Miranda warnings, the defendant said he understood his rights and wanted to speak with an attorney before giving a statement. (Id. at pp. 286-287.) The defendant pled not guilty by reason of insanity and presented expert testimony that he suffered from paranoid schizophrenia and was unable to distinguish right from wrong at the time of the alleged offense. Wainwright rejected the prosecution's argument that Doyle did not apply where the issue was proof of sanity rather than proof of commission of the underlying offense. (Id. at p. 292.) "The point of the Doyle holding is that it is fundamentally unfair to promise an arrested person that his silence will not be used against him and thereafter to breach that promise by using the silence to impeach his trial testimony. It is equally unfair to breach that promise by using silence to overcome a defendant's plea of insanity. In both situations, the State gives warnings to protect constitutional rights and implicitly promises that any exercise of those rights will not be penalized. In both situations, the State then seeks to make use of the defendant's exercise of those rights in obtaining his conviction. The implicit promise, the breach, and the consequent penalty are identical in both situations." (Ibid.) In Wainwright v. Greenfield, the defendant's due process rights were violated when the prosecutor used evidence of his postarrest post-Miranda silence to prove his sanity at the time he committed the offense. ( Wainwright v. Greenfield, supra, 474 U.S. at p. 295.) Relying on Doyle v. Ohio (1976) 426 U.S. 610, the Supreme Court reasoned it is fundamentally unfair to breach the implied assurance of the Miranda warnings that postarrest silence will not be used against the defendant at trial by using his silence "to overcome a defendant's plea of insanity." ( Wainwright v. Greenfield, supra, 474 U.S. at p. 292.) The Court concluded, "what is impermissible is the evidentiary use of an individual's exercise of his constitutional rights after the State's assurance that the invocation of those rights will not be penalized." ( Id. at p. 295.)