Marrero (defendant), a federal corrections officer, was arrested in Manhattan at a social club for unlicensed possession of a loaded .38 caliber pistol in violation of state law. Penal Law § 265.02(a)(1)(a) expressly exempted “peace officers,” from the statute. The term “peace officers” was defined by the statute to include “correction officers of any state correctional facility or of any penal correctional institution.” Marrero’s pretrial motion to dismiss the indictment was granted by the trial court on the ground that he was a “peace officer” as defined under the law. The appellate division reversed and reinstated the indictment, holding that Marrero was not a “peace officer” within the meaning of the exemption. Marrero was thereafter tried by jury and found guilty. The trial court rejected Marrero’s request for a jury instruction that would have allowed the jurors to consider his reasonable belief that the statutory exemption for peace officers applied to him as a defense. The appellate division affirmed the conviction and Marrero appealed.