Twitter fights off demand to identify online Trump critic

An attempt by US authorities to identify an anonymous critic of President Donald Trump on Twitter has set off alarm bells among both Democratic and Republican lawmakers and civil liberties advocates who fear a crackdown on dissent.

Twitter on Friday succeeded in resisting a demand for records about a Twitter account called ALT Immigration (@ALT_uscis), which pokes fun at Trump's immigration policies and appears to be run by one or more federal employees.

The US government withdrew an administrative summons that Customs agents had sent the company in March demanding the records.

But the government backed away only after Twitter filed a federal lawsuit accusing it of violating the First Amendment's protection of free speech.

Customs agents could still continue the investigation using some other methods, civil liberties attorneys said, according to Reuters.

Although authorities retreated, the case has laid bare the broad power of the US government to demand information from technology companies, sometimes with no oversight from the courts and often with built-in secrecy provisions that prevent the public from knowing what the government is seeking.

The summons that Twitter received came from agents who investigate corruption and misconduct within US Customs and Border Control (CBP). Even after it was withdrawn, some lawmakers had questions about the agency's actions.

"CBP must ensure that any properly authorized investigation does not disregard the rights to free speech enshrined in the First Amendment to the US Constitution," two Republican US senators,  Cory Gardner of  Colorado and Mike Lee of Utah, wrote in a letter on Friday to  Secretary .

The senators asked whether the agency would ever ask a private company to divulge private records about a customer based solely on "non-criminal speech". Senate Democrat Ron Wyden of Oregon called for an investigation of whether customs agents had violated a law by retaliating against an internal critic.

The Department of Homeland Security plans to respond directly to the senators, an official said on Friday.

In the case of ALT Immigration, Twitter said it was not bound to keep the summons a secret, and the company informed the account holder of the government demand. That person then found legal representation with the ACLU.

Twitter has declined to say if it has received any other government demands to reveal such anti-Trump critics.