Twitter has sued the U.S Government over a demand for records of an anti-Trump account, according court documents that were obtained by TheWrap.

The suit was filed on Thursday in Northern California District Court, claiming the U.S. Customs and Border Protection tried to use a “limited-purpose investigatory tool” to unmask the owner of the Twitter account “@ALT_USCIS.”

The Department of Homeland Security wanted to uncover the identity of the anonymous user of the account and Twitter argues that unmasking the user would be a violation of the First Amendment. The social media giant’s suit focuses on whether or not the government has the legal authority to make such a request.

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“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 suit said.

In the court document, Twitter argues that revealing the user “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.”

Following Trump’s inauguration on Jan. 20, anonymous Twitter feeds voicing concerns of more than a dozen U.S. government agencies started to pop up and seemed to challenge Trump’s views on a variety of political topics. The @ALT_uscis account features the acronym CIS, which refers to U.S. Citizenship and Immigration Services.

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The account in question sent the following tweet on Thursday after the suit was filed:

Twitter argues in the suit that users’ political speech is protected by the Supreme Court.

The document cites various twitter accounts, including @ALT_uscis for expressing “dissent in a range of different ways,” using the below tweet as an illustration:



The lawsuit names the Department of Homeland Security, Customs and Border Protection, DHS secretary John Kelly, acting CBP commissioner Kevin McAleenan, and special agents Stephen P. Caruso and Adam Hoffman as defendants.