Courthouse News Service is reporting that the US Government has successfully gagged Twitter and Yahoo from "from discussing a federal grand jury subpoena regarding an alleged felony."

Late last month, U.S. District Judge Richard Roberts, chief judge for the District of Columbia, overturned a pair of orders by a federal magistrate judge, regarding the government's attempt to keep them from telling anyone about the existence or content of the grand jury subpoena.

The ruling follows a previous ruling in April by U.S. Magistrate Judge John Facciola in which the government was ordered to file a redacted version of their gag order publicly so Twitter would have the opportunity to respond to the demand. The new ruling overturns Facciola's order, meaning Twitter and Yahoo have no ability to fight the gag in court.

Obviously it's unclear what the subpoena itself relates to -- the investigation is described only as a "felony" in otherwise entirely redacted court documents -- but the ruling is notable because it's firmly at odds with Twitter's generally solid track record of telling users in the US when their data has been subpoenaed by the government. Now the company will be subject to extremely strict criminal penalties if it tips off the user(s) in question over the request.

Speaking late last year at a PandoMonthly event in San Francisco, Twitter CEO Dick Costolo talked about the company's self appointed role as head of the "free speech wing of the free speech party."

"We've been very clear about our desire to make sure that our users have the... another one of our core values is defend and respect the user's voice. We have invested significant time and resources and money into trying to make sure our users can defend themselves and defend requests for their information. We did so in the Wikileaks case, we have done so in many other cases."