Twitter is suing the Donald Trump administration after it attempted to press the social networking company to reveal the identity of a user who had been tweeting criticisms of President Trump.

The lawsuit was filed in the United States District Court in the Northern District of California and lists the U.S. Department of Homeland Security, U.S. Customs and Border Protection (CPD), Secretary of Homeland Security John Kelly and CBP acting commissioner Kevin McAleenan among the defendants.

According to the 32-page suit, the Department of Homeland Security demanded Twitter reveal the user behind the account @ALT_USCIS, an anonymous account that has tweeted criticisms of the Trump administration its foreign policy and actions on immigration.

The @ALT_USCIS account appeared on Twitter in January as part of a flood of “alternative” accounts that purport to be rogue versions of official government agency accounts run by government employees who oppose the current administration.

According to Twitter, accounts like @ALT_USCIS “appear to view and depend on preservation of their anonymity as crucial to their ability to express information and ideas that are contrary to the policies and objectives of the Administration and its agencies.”

The government request for the unmasking came in March. According to the suit, the CBP ordered Twitter to produce information about the account on March 14 and demanded all usernames, account logins, phone numbers, mailing addresses and IP addresses associated with the @ALT_USCIS account. The summons from CBP demanded Twitter produce the information by March 13—a day before the summons was sent.

In the suit, Twitter argues the request from the Department of Homeland security amounts to an “unlawful” use of government powers and threatens the right to free speech enjoyed by the company’s users.

Twitter declined to comment on the case beyond what it filed in court.

The owner of the Twitter account wiped of all its contents earlier this week and did not disclose a reason. According to the suit, Twitter informed the account holder of the CBP summons, which may have prompted the account holder to clear the account. The @ALT_USCIS account acknowledged the case Thursday by tweeting the First Amendment of the U.S. Constitution.

In response to the lawsuit, the American Civil Liberties Union tweeted, "We're glad Twitter is pushing back. We'll be going to court to defend this user's right to anonymous speech."