In North Carolina v. Butler, 441 U.S. 369 (1979), the United States Supreme Court explained that the refusal to sign a waiver is not determinative of the admissibility issue and that a defendant may be considered to have waived his Miranda rights in the absence of a signed waiver form. In Butler, the defendant stated that he understood his Miranda rights and would talk to the detective. The North Carolina Supreme Court had ruled that a custodial statement could not be used unless the defendant had explicitly waived his right to counsel. The United States Supreme Court rejected that per se rule, reasoning as follows: "An express written or oral statement of waiver of the right to remain silent or of the right to counsel is usually strong proof of the validity of that waiver, but is not inevitably either necessary or sufficient to establish waiver. The question is not one of form, but rather whether the defendant in fact knowingly and voluntarily waived the rights delineated in the Miranda case. As was unequivocally said in Miranda, mere silence is not enough. That does not mean that the defendant's silence, coupled with an understanding of his rights and a course of conduct indicating waiver, may never support a conclusion that a defendant has waived his rights. The courts must presume that a defendant did not waive his rights; the prosecution's burden is great; but in at least some cases waiver can be clearly inferred from the actions and words of the person interrogated." (441 U.S. at 373.)