The ACLU requested information on how often police obtain cellphone location data and how much money they spend tracking cellphones. The requests also asked whether police demonstrate probable cause and obtain a warrant before accessing the data.
Apple came under scrutiny after reports in April revealed iPhones store data on their locations.
Last month, Matthew Olsen, nominated to head the National Counterterrorism Center, told a Senate panel that the government might have the authority under the PATRIOT Act to track Americans using their cellphone data.
Sen. Ron Wyden (D-Ore.) and Rep. Jason Chaffetz (R-Utah) introduced bills in June to create guidelines for when the government can track cellphone data.
Also in June, Sens. Al Franken (D-Minn.) and Richard Blumenthal (D-Conn.) introduced a measure that would require firms such as Apple and Google along with app developers to obtain consent before collecting or sharing consumers' location data.