As major tech companies petition the White House for data collection reform, the American Civil Liberties Union (ACLU) Monday released a press release that highlights the rising number of law enforcements requests for cell phone subscriber data in 2012. 

The release pointed out that in 2012 alone AT&T and T-Mobile documented over 600,000 requests for customer information made by local, state and federal law enforcement. 

The nation’s major cellphone carriers made the numbers available in response to an inquiry from Sen. Edward Markey (D-Mass.).

Verizon, in its response to Sen. Markey’s request, said that police requests for customers’ call records have approximately doubled over the last five years. The ACLU notes that often no warrant is required to compel cellphone carriers to turn over their customers’ information to police.

Christopher Calabrese, legislative counsel at the ACLU’s Washington Legislative Office said in a statement that there is no doubt that law enforcement sees mobile devices as the go-to source for information, likely in part because of the lack of privacy protections afforded by the law. 

"Our mobile devices quite literally store our most intimate thoughts as well as the details of our personal lives," Calabrese wrote. "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."

The ACLU also notes that the carrier responses to Sen. Markey’s office also show that law enforcement conducts real-time surveillance of targets' web browsing habits. 

According to AT&T’s letter, the company allows law enforcement to do real time web browsing surveillance. Police are also requesting "tower dumps," whereby cellphone companies give law enforcement the records of all cellphone users who have connected to a particular cellphone tower in a given time range.

The news comes as even more details surface about the NSA's extensive digital surveillance programs. Just last week, the Washington Post published a report that showed the NSA records and stores global cell phone location data.  

In a letter to U.S. President Barack Obama, major tech companies in the United States are asking for a reform of government data collection practices. 

"The balance in many countries has tipped too far in favor of the state and away from the rights of the individual — rights that are enshrined in our Constitution," the letter said. "This undermines the freedoms we all cherish. It's time for a change."