Federal, state and local law enforcement agencies issued about 1.1 million requests for cellphone information in 2012, according to data provided to a Democratic senator.
The statistics do not include National Security Agency surveillance or other classified programs.
Eight major cellphone service providers revealed the data in response to letters from Sen. Ed MarkeyEd MarkeyOvernight Energy: Trump set to sign offshore drilling order Sanders: Trump couldn't be 'more wrong' on climate Overnight Cybersecurity: Ex-officials warn 'Buy American' might harm Pentagon cybersecurity | Chair nudges Trump on cyber order | House gets security training MORE (D-Mass.). The 1.1 million requests do not include Sprint subscribers because the company said it would be impractical to provide an exact total.
Markey expressed particular concern over "cellphone tower dumps," in which police request all of the phone numbers that connected to a particular cell tower within a specific time period.
The carriers reported about 9,000 cell tower dumps in 2012, potentially covering hundreds of thousands of phone numbers, although not all of the companies provided a figure for the surveillance technique.
The responses also showed varying standards for how long the carriers retain different types of information.
The carriers charged police hefty fees for the information on their customers. In 2012, AT&T received $10 million for surveillance compliance, T-Mobile received $11 million, and Verizon received less than $5 million.
“As law enforcement uses new technology to protect the public from harm, we also must protect the information of innocent Americans from misuse,” Markey said in a statement. “We need a 4th Amendment for the 21st century. Disclosure of personal information from wireless devices raises significant legal and privacy concerns, particularly for innocent consumers."
He said he plans to introduce legislation to curb bulk requests for data, such as tower dumps. He would also require a warrant, based on probable cause, for access to any information on a customer's location.
His bill would direct the Federal Communications Commission to limit how long carriers could retain a customer's information. It would also require regular disclosures from law enforcement agencies about their surveillance requests.
“If the police want to know where you are, we should know why,” Markey said. “When law enforcement access location information, it's as sensitive and personal as searching an individual’s home and should be treated commensurately.”
Chris Calabrese, a lobbyist for the American Civil Liberties Union, said police see mobile devices as the "go-to source for information," in part because of a lack of stringent privacy safeguards.
“Our mobile devices quite literally store our most intimate thoughts as well as the details of our personal lives," Calabrese said in a statement. "The idea that police can obtain such a rich treasure trove of data about any one of us without appropriate judicial oversight should send shivers down our spines.”