In Bullington v. Missouri, 451 U.S. 430 (1981), the Court held that the Double Jeopardy Clause does apply to capital-sentencing proceedings where such proceedings "have the hallmarks of the trial on guilt or innocence." Id., at 439. The Court identified several aspects of Missouri's sentencing proceeding that resembled a trial, including the requirement that the prosecution prove certain statutorily defined facts beyond a reasonable doubt to support a sentence of death. Id., at 438. Such a procedure, the Court explained, "explicitly requires the jury to determine whether the prosecution has `proved its case.'" Id., at 444. Since, the Court concluded, a sentence of life imprisonment signifies that "`the jury has already acquitted the defendant of whatever was necessary to impose the death sentence,'" the Double Jeopardy Clause bars a State from seeking the death penalty on retrial. Id., at 445 (quoting State ex rel. Westfall v. Mason, 594 S. W. 2d 908, 922 (Mo. 1980) (Bardgett, C. J., dissenting)).