Can a district court declare a mistrial and retry a defendant without violating the prohibition against double jeopardy?

A district court may declare a mistrial and retry a defendant without violating the prohibition against double jeopardy when there is a manifest necessity for the discharge of the original proceeding. See Arizona v. Washington , 434 U.S. 497, 509 (1978). A hung jury is the classic example of manifest necessity. See Washington, 434 U.S. at 509; see also Richardson v. United States, 468 U.S. 317, 326 (1984) ("[A] trial court's declaration of a mistrial following a hung jury is not an event that terminates the original jeopardy to which petitioner was subjected."). "The trial judge's decision to declare a mistrial when he considers the jury deadlocked is . . . accorded great deference by a reviewing court. " Washington, 434 U.S. at 510.

In determining whether to declare a mistrial because of jury deadlock, relevant factors for the district court to consider include the jury's collective opinion that it cannot agree, the length of the trial and complexity of the issues, the length of time the jury has deliberated, whether the defendant has objected to a mistrial, and the effects of exhaustion or coercion on the jury. See United States v. Cawley , 630 F.2d 1345, 1348-49 (9th Cir. 1980). "The most critical factor is the jury's own statement that it is unable to reach a verdict. " Id. at 1349. Without more, however, such a statement is insufficient to support a declaration of a mistrial. See id. On receiving word from the jury that it cannot reach a verdict, the district court must question the jury to determine independently whether further deliberations might overcome the deadlock. See id. at 1349.