implied waivers

In 1976, Donald Bolles, a reporter for the Arizona Republic, was fatally injured when a dynamite bomb exploded underneath his car. Respondent was arrested and charged with first-degree murder in connection with Bolles' death. Shortly after his trial had commenced, while jury selection was underway, respondent and the state prosecutor reached an agreement whereby respondent agreed to plead guilty to a charge of second-degree murder and to testify against two other individuals — Max Dunlap and James Robison — who were allegedly involved in Bolles' murder. Specifically, respondent agreed to "testify fully and completely in any Court, State or Federal, when requested by proper authorities against any and all parties involved in the murder of Don Bolles . . . ." The agreement provided that "[s]hould the defendant refuse to testify or should he at any time testify untruthfully . . . then this entire agreement is null and void and the original charge will be automatically reinstated." The parties agreed that respondent would receive a prison sentence of 48-49 years, with a total incarceration time of 20 years and 2 months. In January 1977, the state trial court accepted the plea agreement and the proposed sentence, but withheld imposition of the sentence. Thereafter, respondent testified as obligated under the agreement, and both Dunlap and Robison were convicted of the first-degree murder of Bolles. In February 1980, the Arizona Supreme Court reversed the convictions of Dunlap and Robison and remanded their cases for retrial. The State sought respondent's cooperation and testimony in preparation for the retrial of Dunlap and Robison. On April 3, 1980, however, respondent's counsel informed the prosecutor that respondent believed his obligation to provide testimony under the agreement had terminated when he was sentenced. Respondent would again testify against Dunlap and Robison only if additional conditions were met, including, among others, that the State release him from custody following the retrial. On April 9, 1980, the State informed respondent's attorney that it deemed respondent to be in breach of the plea agreement. On April 18, 1980, the State called respondent to testify in pretrial proceedings. In response to questions, and upon advice of counsel, respondent invoked his Fifth Amendment privilege against self-incrimination. On May 8, 1980, the State filed a new information charging respondent with first-degree murder. Respondent's motion to quash the information on double jeopardy grounds was denied. The Arizona Supreme Court, after reviewing the plea agreement, the transcripts of the plea hearing and the sentencing hearing, respondent's April 3 letter to the state prosecutor, and the prosecutor's April 9 response to that letter, held that the plea agreement contemplated availability of respondent's testimony whether at trial or retrial after reversal, that respondent violated the terms of the plea agreement, vacated respondent's second-degree murder conviction, reinstated the original charge, and dismissed the new information. After these rulings, respondent offered to testify at the retrials, but the State declined his offer. Respondent was then convicted of first-degree murder and sentenced to death. The judgment was affirmed on direct appeal. Respondent sought federal habeas corpus for the second time. The District Court dismissed the petition; a Court of Appeals panel affirmed. The Court of Appeals went en banc, held that the State had violated respondent's rights under the Double Jeopardy Clause, and directed the issuance of a writ of habeas corpus. We granted the State's petition for a writ of certiorari to review the Court of Appeals' decision.