“The underlying idea . . . is that the State with all its resources and power should not be allowed to make repeated attempts to convict an individual for an alleged offense, thereby subjecting him to embarrassment, expense and ordeal and compelling him to live in a continuing state of anxiety and insecurity, as well as enhancing the possibility that even though innocent he may be found guilty.” Green v. United States, 355 U. S. 184, 187–188 (1957).If the Government cannot prove its case beyond a reasonable doubt at a trial, that should be it: “A power in government to subject the individual to repeated prosecutions for the same offense would cut deeply into the framework of procedural protections which the Constitution establishes for the conduct of a criminal trial.” United States v. Jorn, 400 U. S. 470, 479 (1971) (Harlan, J., plurality opinion).
Justice Stevens (in his dissent in Renico v. Leit) pointed out the lengths that judges at common law would push juries to reach a verdict because the thought of a second trial because of a hung jury was too much (cleaned up without footnotes):
At common law, courts went to great lengths to ensure the jury reached a verdict. Fourteenth-century English judges reportedly loaded hung juries into oxcarts and carried them from town to town until a judgment“‘bounced out.’” Less enterprising colleagues kept jurors as de facto “prisoners” until they achieved unanimity. The notion of a mistrial based on jury deadlock did not appear in Blackstone’s Commentaries; it is no surprise, then, that colonial juries virtually always returned a verdict. Well into the 19th and even the 20th century, some American judges continued to coax unresolved juries toward consensus by threatening to deprive them of heat, sleep, or sustenance or to lock them in a room for a pro-longed period of time.In our own District, there was a mistrial for a defendant last week after an 8-week mortgage fraud trial. The prosecution should not be permitted to retry that defendant. It's just not fair to have to fight the power of the Government a second time even if the mistrial was necessary because of a hung jury.
Mercifully, our legal system has evolved, and such harsh measures are no longer tolerated. Yet what this history demonstrates—and what has not changed—is the respect owed “a defendant’s valued right to have his trial completed by a particular tribunal.” Wade v. Hunter, 336 U. S. 684, 689 (1949). Our longstanding doctrine applying the Double Jeopardy Clause attests to the durability and fundamentality of this interest.