 In the majority opinion, Justice Harry Blackmun rejected the idea that the installation and use of a pen register constitutes a violation of the "legitimate expectation of privacy" since the telephone numbers would be available to and recorded by the phone company anyway.In "Katz v. United States" (1967), the United States Supreme Court established its "reasonable expectation of privacy" test, which overturned a 1928 precedent established in "Olmstead v. United States" and held that the use of a covert listening device (bug) was not a constitutionally protected search without first obtaining a warrant, because there was a reasonable expectation that the communication would be private.The government was therefore required to get a warrant to execute a search using a bug.