Does the district court err in failing to instruct the jury that striking does not include quitting because of abnormally dangerous working conditions?

Fifth, the district court did not err in failing to instruct the jury that "striking" does not include quitting because of abnormally dangerous working conditions. The evidence defendants might have introduced to support such an instruction could come in only under the defenses of necessity or duress. See United States v. Lowe, 654 F.2d 562, 566-67 (9th Cir.1981) (necessity); United States v. Hernandez, 608 F.2d 741, 750 (9th Cir.1979) (duress). Prior to trial, the government made a motion to exclude evidence on these defenses. Defendants did not oppose the motion. It is not error to fail to give a requested instruction where the evidence to support that instruction has been excluded without objection. ⁸