What is the test for providing an alibi in a criminal case?

A defendant is entitled, upon proper request, to an instruction submitting to the jury any defense theory for which there is a foundation in the evidence. See United States v. Pedroza, 750 F.2d 187, 205 (2d Cir.1984). We have previously stated that, "[a]s a general rule, we think it best for [alibi] instructions to be given where alibi is claimed." United States v. Burse, 531 F.2d 1151, 1153 (2d Cir.1976). A proper alibi instruction informs the jury that, in order to gain an acquittal, the defendant need not prove an alibi defense but need only raise a reasonable doubt as to his or her presence at the scene of the crime. Id. The instruction prevents the jury from concluding that the failure to prove an alibi defense is a sign of the defendant's guilt. Id.