In a "victory for Twitter, the social media service dismisses a lawsuit that argued the U.S. government was attempting to quell anonymous speech critical of immigration policies.

On Friday, Twitter withdrew its lawsuit against the U.S. Homeland Security Department over a summons that demanded information about the individual(s) behind @ALT_USCIS, an account from those claiming to be employees of the United States Citizenship and Immigration Services challenging the agency's policies and management.

Twitter said that the U.S. government had withdrawn a summons for records about who was behind the @ALT_USCIS Twitter account.

It is not clear why the government had withdrawn the summons, or whether it had closed an investigation it said it was conducting.

Twitter cited freedom of speech as a basis for not turning over records about the @ALT_usci account. The use of "ALT" with a government agency acronym has led many to assume government employees are behind such tweets.

The acronym U.S. CIS refers to U.S. Citizenship and Immigration Services, and the account describes itself as "immigration resistance."

Senator Ron Wyden, an Oregon Democrat, sent a separate letter on Friday to U.S. Customs and Border Protection, which is part of Homeland Security, requesting an investigation into why and how the summons was issued.