Twitter announced on Thursday that it was filing a lawsuit against the U.S. Department of Homeland Security over a government demand that they identify the pseudonymous user behind the @ALT_USCIS account, a Twitter account critical of the department's customs and immigration policies. Within hours, the ACLU announced they'll be representing that unidentified user.
“The right to anonymously speak out against the government is clearly protected by the First Amendment. We are pleased to see Twitter standing up for its users’ rights, and the ACLU will soon be filing documents in court on behalf of this user," ACLU attorney Nathan Freed Wessler told BuzzFeed News in a statement.
From the provided documents, there seems to be no legal reason for a Customs and Border Patrol agent to be seeking the information other than as a fishing expedition. The law cited to justify unmasking the author deals with investigations relating to imported goods; unless the government is accusing @ALT_USCIS of not paying the proper import duties on certain tweets, it's unclear what possible action the Twitter account author could have taken that would run afoul of this law.
In fact, the government agents gave Twitter no explanation whatsoever for their "investigation," legal or otherwise, thus leading Twitter to file a lawsuit blocking the demand on First Amendment grounds. Being critical of immigration policy is not, of itself, against any law, and certainly does not fall within the bounds of something that can be legally investigated by customs officers acting under laws specifically intended to investigate imported merchandise.
Filing the lawsuit appears to be the right thing for Twitter to have done. It is not, however, where this should end. The government needs to better explain this apparent attempt to silence a critic, because if it's what it looks like somebody who is not "@ALT_USCIS" should be investigated at length.