The American Civil Liberties Union is suing federal authorities over their alleged use of cellphone location data — particularly in immigration enforcement.

The nonprofit organization today filed a lawsuit against the Department of Homeland Security, U.S. Customs and Border Protection and U.S. Immigration and Customs Enforcement to force the agencies to release records about purchasing cellphone location data for immigration enforcement and other purposes. The lawsuit follows multiple news reports earlier this year about the Trump administration buying access to commercial databases that track cellphone locations and then using that data to detect people who might be entering the country illegally.

“It’s critical we uncover how federal agencies are accessing bulk databases of Americans’ location data and why,” Nathan Freed Wessler, senior staff attorney with the ACLU's Speech, Privacy, and Technology Project, said in a statement. “There can be no accountability without transparency.”

Senate Democrats, such as privacy advocate Sen. Ron Wyden (D-Ore.), had written a letter to DHS asking for more information on how such data was being used. On Wednesday morning, they disclosed that the department's inspector general would take up the matter.