The American Civil Liberties Union has filed an administrative complaint with the federal government after a US citizen was detained at the border and forced to unlock his iPhone SE. Aaron Gach, an artist and activist who was holding an exhibition in Belgium, was subjected to interrogation by US Customs and Border Protection upon his reentry into the country at San Francisco International Airport in February. Gach was forced to unlock his phone, and in doing so the ACLU says CBP agents violated Gach’s constitutional rights, specifically his Fourth Amendment right protecting him from unlawful search and seizure.

The ACLU is now seeking more information as to how CBP searches electronic devices at the border and what it might do with potential data it collects, as well as requesting new rules around warrants and probable cause for device searches. Gach was reportedly asked about his art and for contact information on his associates in the art scene. Gach’s art exhibition in Brussels also featured works on “mass incarceration, government control, and political dissent,” the ACLU says, raising concerns that Gach was targeted specifically for his political activism.

CBP then asked for access to Gach’s iPhone SE, which contained sensitive information, communications with friends and family, and social media accounts. Similar to US-born NASA scientist Sidd Bikkannavar, who was detained at the border in February until he too unlocked his smartphone, Gach felt pressured to hand his phone over for fear of being detained for an indefinite amount of time. It’s unclear if agents copied data from Gach’s iPhone, though CBP officials took his device out of sight for more than 10 minutes. Though the government claims it has the authority to search electronic devices at the border, the manner in which it does so is highly controversial. (The only definite way to prevent unlawful seizure of your data is to delete it before you fly.)

The ACLU says CBP consistently violates US citizens’ privacy rights, which extend to information on a smartphone thanks to the Supreme Court case Riley v. California. They do so by treating the border as a more legally lenient territory for the US government, allowing agents to coerce detainees into handing over access without the lawful use of a warrant or the presence of any form of probable cause. CBP searches are also on the rise since Trump took office, the ACLU says, with officers notching 2,700 searches in January and another 2,200 in February. That far outpaces 2016 levels, in which 19,000 searches were conducted throughout the entire year.

Taking the matter even further, the ACLU has filed a Freedom of Information Act request demanding information about CBP compliance with a 2013 appeals court decision restricting government border searches of electronic devices. The ACLU is also supporting a new bill, introduced last month by Ron Wyden (D-OR), called the Protecting Data at the Border Act. The proposal would prohibit access to individuals’ “electronic equipment” without the establishing of probable cause. It would also prevent CBP officials from denying entry to the country based on whether someone provides passwords, PIN numbers, or any other form of authentication including biometric data.