The petitioner was convicted in the District Court for the Southern District of California under an eight-count indictment charging him with transmitting wagering information by telephone from Los Angeles to Miami and Boston, in violation of a federal statute. At trial the Government was permitted, over the petitioners objection, to introduce evidence of the petitioners end of telephone conversations, overheard by FBI agents who had attached an electronic listening and recording device to the outside of the public telephone booth from which he had placed his calls. In affirming his conviction, the Court of Appeals rejected the contention that the recordings had been obtained in violation of the Fourth Amendment,
