Flying sucks enough as it is, but a Transportation Security Administration employee deciding to root around in your laptop or cellphone can make it even worse. This practice of searching electronic devices has been going on for years at international airports, but this was limited to travelers flying in and out of the US. Recently there has a large uptick in the number of devices searched by Customs and Border Protection agents: Last year, CBP officials searched 30,000 devices, up from just 5,000 in 2015.

Last October, the TSA announced it would ramp up its own screening of electronic devices for domestic passengers, but hasn’t published any information on policies surrounding this practice, or how many searches have been conducted. On Monday, the American Civil Liberties Union Foundation of Northern California announced it had filed a FOIA lawsuit demanding government documents about the practice.

The ACLU Foundation of Northern California had previously sought these documents through a FOIA request last December, but the TSA didn’t provide the documents.

“TSA is searching the electronic devices of domestic passengers, but without offering any reason for the search,” Vasudha Talla, a staff attorney with the ACLU Foundation of Northern California, said in a statement. “We don’t know why the government is singling out some passengers, and we don’t know what exactly TSA is searching on the devices. Our phones and laptops contain very personal information, and the federal government should not be digging through our digital data without a warrant.”

Read More: The US Government Can Download the Entire Contents of Your Computer at Border Crossings

The issue of warrantless searches at airports has been a major issue for the ACLU and other civil rights organizations like the Electronic Frontier Foundation for years. Although the US Supreme Court ruled in 2014 that a cop has to get a warrant before searching the cell phone of someone who has been arrested, the CBP has argued that this legal protection against warrantless searches doesn’t apply at the US border.

The problem is that TSA is searching the electronic devices of US citizens taking domestic flights, not just passengers entering or leaving the US. As the ACLU details in its FOIA lawsuit, this includes the use of devices such as the Cellebrite Universal Forensic Extraction Device, which can be used to extract information from a cellphone’s SIM cards and is used by the TSA at every airport in California.