Is it reversible error to refuse an alibi defense?

The introduction of an alibi defense frequently poses the risk that if the alibi evidence is disbelieved, the defense will backfire, leading the jury to convict because of the failure of the defense rather than because the evidence introduced by the government has satisfied the jury of the defendant's guilt beyond a reasonable doubt. Because of this possibility of confusion on the jury's part, we have, on appeal from federal convictions, held that it is reversible error to refuse a defendant's request to the effect that, even if the alibi witnesses are disbelieved, the burden of proof remains with the government. United States v. Burse, 531 F.2d 1151 (2d Cir. 1976).