In the United States v. New York Telephone Co., 1977, the Supreme Court ruled that federal courts have the authority to order a telephone company to assist law enforcement in executing a pen register warrant. A pen register is a device used by law enforcement agencies to record all numbers dialed from a particular phone line. The case arose when New York Telephone Company refused to install such devices on its premises at the request of government officials who had obtained warrants for their use in an investigation into illegal gambling operations. The company argued that it was not legally obligated under Title III of Omnibus Crime Control and Safe Streets Act of 1968, which governs wiretapping and electronic surveillance by authorities, as well as Federal Rule of Criminal Procedure 41 (which allows judges or magistrates to issue search warrants) because they did not specifically mention this kind of assistance from third parties like themselves. However, the court held with majority decision that these laws implicitly include such power due to broad language authorizing "all necessary steps" for execution.

In the dissenting opinion for United States v. New York Telephone Co., Justice William J. Brennan Jr., joined by Justices Potter Stewart and Thurgood Marshall, argued that the majority's decision to allow pen registers without a warrant was an overreach of judicial power. They contended that Congress had not granted such authority in Title III of the Omnibus Crime Control and Safe Streets Act of 1968 or any other legislation, nor did they believe it could be inferred from Rule 41(b) which governs search warrants. The dissenters also expressed concern about potential privacy violations arising from this ruling, as it would permit government surveillance without probable cause or oversight by neutral magistrates - conditions typically required for lawful searches under Fourth Amendment jurisprudence.