The following excerpt is from U.S. v. Hightower, 106 F.3d 410 (9th Cir. 1997):
To invoke the necessity defense, the defendant must show that: (1) he was faced with a choice of evils and chose the lesser evil; (2) he acted to prevent imminent harm; (3) he reasonably anticipated a direct causal relationship between his conduct and the harm to be averted; and (4) he had no legal alternatives to violating the law. See United States v. Schoon, 971 F.2d 193, 195 (9th Cir.1991).
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