HAYNES v. UNITED STATES, 390 U.S. 85 (1968) -- A 1968 SCOTUS case holding that "a proper claim of the constitutional privilege against self-incrimination provides a full defense to prosecutions either for failure to register a firearm under [26 U.S.C.] 5841 or for possession of an unregistered firearm under [26 U.S.C.] 5851." In other words, prohibited persons in illegal possession of firearms cannot be convicted of failing to register firearms, or possession of unregistered firearms, where such is required, on the basis that requiring registration by those in illegal possession would violate such persons' Fifth Amendment rights.