Twitter is suing the Trump administration after the Department of Homeland Security tried to compel the social-media company to unmask an anonymous anti-Trump account. According to the lawsuit, filed Thursday in a Northern California District Court, Twitter received a demand from the Department of Homeland Security in March that it reveal the owner of the @ALT_USCIS account, which tweets about Trump’s immigration policies under the guise of a dissenting employee at the U.S. Citizenship and Immigration Services agency. Reuters, which first broke the news on Thursday afternoon, reports that the government requested I.P. logs, mailing addresses, and phone numbers related to the account.

The @ALT_USCIS account responded by tweeting a screenshot of the text of the First Amendment:

Twitter asserts that the records request is a threat to free speech. “The rights of free speech afforded Twitter’s users and Twitter itself under the First Amendment of the U.S. Constitution include a right to disseminate such anonymous or pseudonymous political speech,” the company wrote in its court filing, adding that complying with the order “would have a grave chilling effect on the speech of that account in particular and on the many other ‘alternative agency’ accounts that have been created to voice dissent to government policies.”

The American Civil Liberties Union says it will be representing the user behind @ALT_USCIS.

It is not the first time that Twitter has sued the federal government over First Amendment issues: in 2014, the San Francisco-based company sued the Department of Justice over its right to reveal surveillance requests from the government to its user base. “This is an important issue for anyone who believes in a strong First Amendment, and we hope to be able to share our complete transparency report,” Twitter said at the time.

The “alt” being targeted by D.H.S. account is just one of several that were created in the wake of Trump’s inauguration, after the president issued a gag order on social-media accounts for several government agencies, including the National Park Service, which provoked Trump by retweeting a photo comparing the inauguration crowds in 2009 and 2017, and later tweeting out climate change facts. The Park Service rebellion, which was quickly put down, spawned a wave of “alternative” or “rogue” government accounts, none of which have been verified or proved to have anything to do with the agencies they claim to represent. The alternative U.S.C.I.S. account, Twitter says in its complaint, serves “to express public criticism of the Department and the current administration.”

Twitter users were quick to weigh in on the news.

Update: On Friday, Twitter dropped its case against the federal government after U.S. Customs and Border Protection withdrew its summons for information regarding the identity of the owner of the @ALT_USCIS account.