The Oregon senator sent a letter late on Friday to Kevin McAleenan, acting commissioner of the United States Customs and Border Control (USCBP), requesting that the agency conduct an internal investigation of why it sent a summons to Twitter demanding the unmasking of the user behind a Twitter account critical of the Trump administration. In the letter, Wyden asserts that the summons looks like an attempt to stifle free speech, and appears to far exceed the legal authority of the CBP.
The letter comes after Wyden called the government's action a "witch hunt" in a statement Thursday night. That came in response to news earlier in the day that Twitter had filed a lawsuit in a San Francisco federal court Thursday to block the CBP summons, which was originally transmitted March 14.
The Twitter account in question is @ALT_uscis, which apes the name of a real government agency, describes itself as "immigration resistance," and tweets anti-Trump messages. The Trump administration believes the account could be owned by at least one government employee, which would make the CBP's summons look like a measure to prevent leaks.