“ Inasmuch as petitioner's refusal to answer related to questions not clearly pertinent to the subject on which the two-member subcommittee conducting the hearing had been authorized to take testimony, the conditions necessary to sustain a conviction for deliberately refusing to answer questions pertinent to the authorized subject matter of a congressional hearing are wanting. Watkins v. United States, supra. The judgment of the Court of Appeals is therefore reversed and the cause remanded to the District Court with directions to dismiss the indictment. ”