Investigators Need a Warrant to Get Call Content

San Francisco - The Electronic Frontier Foundation (EFF) and the Center for Democracy and Technology (CDT) filed an amicus brief last Friday arguing that the government needs a warrant to collect the content of a telephone call, even if that content came from digits dialed on a phone keypad.

A federal magistrate judge in Texas asked EFF to file the brief in response to requests from government investigators to use a pen register or trap and trace device to collect all information entered using the buttons on a telephone (including, for example, bank account numbers or prescription refill requests). A "pen/trap" order must meet a lower standard of judicial review than a typical phone-tapping warrant, because only telephone numbers dialed from a certain phone -- not the content of the phone call itself -- are normally collected.

In their brief, EFF and CDT ask the judge to continue denying the orders and argue that the government's request cannot be granted without violating federal wiretap law and the Fourth Amendment.

"After the phone call has been connected, the pen/trap device's job is over," said EFF Senior Staff Attorney Lee Tien. "The numbers that you enter through the keypad to fill a prescription or join a meeting are just like the words or passcodes you say when there's no keypad option. They cannot be retrieved without meeting stringent probable cause requirements."

Until Magistrate Judge Smith asked for the brief, these pen/trap requests were unknown to the public. The judge previously asked EFF to respond to the government's secret requests to track cell phone locations without a warrant based on probable cause. Judge Smith as well as several other magistrates around the country have now held that the government cannot track cell phone locations unless it can show probable cause and a judge finds good reason to believe that criminal activity is afoot.

"Just as in the cell tracking cases, the government has tried to hide its baseless arguments from public scrutiny," said EFF Staff Attorney Kevin Bankston. "We commend Judge Smith for taking these issues seriously and allowing EFF to offer a response to the government's contrived reasoning."

For the amicus brief:


Lee Tien
Senior Staff Attorney
Electronic Frontier Foundation

John Morris
Center for Democracy and Technology

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