Assigning the burden to prove an affirmative defense by a preponderance of the evidence to a defendant in a criminal proceeding, and thus to an alleged contemner in a criminal contempt proceeding, is constitutionally permissible. The Supreme Court so held in Martin v. Ohio (1987) 480 U.S. 228 [107 S. Ct. 1098, 94 L. Ed. 2d 267], when it considered the validity under the due process clause of the Fourteenth Amendment of an Ohio statute pursuant to which self-defense was an affirmative defense in a prosecution for murder. Affirmative defenses under Ohio law were those in which ' 'an excuse or justification [was] peculiarly within the knowledge of the accused, on which he can fairly be required to adduce supporting evidence.' ' (480 U.S. at p. 230 [107 S. Ct. at p. 1100].) The high court held that since the state did not preclude the jury from considering self-defense evidence in determining whether there was a reasonable doubt that any element of the offense had been proven, it was permissible to impose on the defendant the burden of proving self-defense by a preponderance of the evidence. (Id. at pp. 233-234 [107 S. Ct. at p. 1102]; ...