April 6 (UPI) — Social media giant Twitter filed a lawsuit Thursday alleging President Donald Trump‘s administration demanded the identity of a user who’s been highly critical of the federal government.

The suit, filed in U.S. District Court in California, names a consortium of defendants — including the U.S. Department of Homeland Security, Customs and Border Protection, Homeland Security Secretary John F. Kelly, CBP acting chief Kevin McAleenan and two CBP special agents.

According to Twitter, the federal government had issued a summons for the identity of the user @ALT_USCIS — which has been critical of the U.S. Citizenship and Immigration Services agency. The user of the account has said they are a government employee.

Twitter, which has long been an advocate of Internet privacy, refused the request to unmask the user, who posted an image of the First Amendment to the U.S. Constitution on Thursday afternoon.

Two CBP agents sent the summons to Twitter last month and said the company was “required to turn over “all records regarding the Twitter account @ALT_USCIS to include, user names, account login, phone numbers, mailing addresses and IP addresses.”

The summons threatened to take Twitter to court if it failed to comply with the order, and asked that the manager of the @ALT_USCIS account not be notified of the government’s actions to identify them.

“The purpose of this request appears to be, and the effect of Twitter’s complying with it likely would be, to enable or help to enable defendants to pierce the anonymity of the person or persons who established and use the @ALT_USCIS account,” the 25-page lawsuit states.

Twitter filed this lawsuit against the federal government on Thursday, claiming that U.S. Customs and Border Patrol agents attempted last month to force the social media giant to identify the user behind an account that’s been substantially critical of the U.S. government on immigration matters. Image courtesy U.S. District Court-Northern District of California

“We’re glad Twitter is pushing back,” the American Civil Liberties Union tweeted. “We’ll be going to court to defend this user’s right to anonymous speech.”

“Twitter’s actions in providing a platform for the dissemination of its users’ speech — including its decision to permit the publication of pseudonymous speech — is fully protected by the First Amendment,” Twitter said.

A CBP spokeswoman said Thursday the agency does not comment on pending litigation.

The lawsuit comes at a time of increasing privacy concerns among citizens and the government.

Last week, Congress sent a bill to Trump’s desk proposing to scrap a web privacy regulation and let Internet service providers sell their customers’ browsing histories without their consent. Two weeks ago, the White House expressed concern about a revelation that members of Trump’s transition were incidentally swept up in foreign surveillance efforts.

Twitter responds: Twitter Sues Government to Stop Unmasking of Anti-Trump Account