Timothy Lee writes: On Monday the Associated Press reported that the Justice Department “secretly obtained two months of telephone records of reporters and editors for The Associated Press.” But here’s what’s really scary: The Justice Department’s actions are likely perfectly legal.

U.S. law allows the government to engage in this type of surveillance—on media organizations or anyone else — without meaningful judicial oversight.

The key here is a legal principle known as the “third party doctrine,” which says that users don’t have Fourth Amendment rights protecting information they voluntarily turn over to someone else. Courts have said that when you dial a phone number, you are voluntarily providing information to your phone company, which is then free to share it with the government.

This all dates back to a 1979 Supreme Court decision. Police had asked the phone company for information about the numbers dialed from a robbery suspect’s phone. The suspect objected, pointing to a famous 1967 ruling holding that the Fourth Amendment requires a warrant to record the audio of a phone call. He argued that the same principle ought to apply when the government records information about the numbers a suspect dials.

The Supreme Court rejected this argument. “We doubt that people in general entertain any actual expectation of privacy in the numbers they dial,” Justice Harry Blackmun wrote for the court. He pointed out that telephone customers are used to seeing numbers they’ve dialed on their monthly telephone bill.

Blackmun’s reasoning may have turned on the fact that automatic dialing was a relatively new development in 1979. Previously, telephone users had to tell a human operator which number they wished to reach, making it plausible to regard the phone company as an active participant in the phone-dialing process, but a mere passive conduit in transmitting the phone call itself.

Technological progress has rendered this distinction increasingly dubious. For example, cell phone companies now keep records about the locations of their customers’ phones. The government has argued that this “non-content” information should be available without a warrant. Yet such records amount to a detailed record of everywhere the phone’s owner has been in the past month; a much more intrusive form of surveillance than a list of the phone numbers a customer has dialed. [Continue reading…]