Before BROWNING and CANBY, Circuit Judges, KELLEHER,* Senior District Judge.

Appellant challenges his conviction for possession of marijuana with intent to distribute, 21 U.S.C. Sections 841(a)(1) and 841(b)(1)(B)(vii), on grounds of double jeopardy. Judge Richard M. Bilby declared a mistrial after closing arguments in Appellant's first trial to permit the government to introduce new evidence at a second trial.

As a general rule "criminal defendants have a right to have the jury first empaneled to try them reach a verdict." United States v. Bates, 917 F.2d 388, 392 (9th Cir.1990). Where, as here, a defendant has not knowingly and intelligently waived his double jeopardy rights retrial is proper only when the mistrial resulted from manifest necessity. Id.

The government argues that the mistrial was manifestly necessary because it was surprised by Appellant's defense of mistaken identity. It urges that a second trial was appropriate to permit it to introduce evidence to rebut this defense. We disagree. Manifest necessity does not justify a mistrial "to help the prosecution, at a trial in which its case is going badly, by affording it another, more favorable opportunity to convict the accused." Gori v. United States, 367 U.S. 364, 369 (1961). Accordingly, Appellant's conviction cannot stand.

REVERSED.