Twitter filed a lawsuit Thursday to block an order from the Department of Homeland Security that seeks to reveal the user of an account who has been critical of the Drumpf administration’s immigration policies.

Tweets from the account — @ALT_uscis — indicate that it is run by someone who is an employee of the U.S. Citizenship and Immigration Services division of Homeland Security.

Free speech advocates said the DHS order appeared to be the first time the government has attempted to use its powers to expose an anonymous critic — a development that, if successful, would have a “grave chilling effect on the speech of that account” as well as other accounts critical of the U.S. government, Twitter said.

DHS is “unlawfully abusing a limited-purpose investigatory tool” to find out who is behind the @ALT_uscis account, according to Twitter’s court filings.

DHS spokeswoman Jenny Burke declined to comment, citing the pending litigation.

Get the rest of the story at the The Washington Post: The government is demanding to know who this Trump critic is. Twitter is suing to keep it a secret. РThe Washington Post