On December 14, Twitter received a bizarre subpoena from the District Attorney of Suffolk County, which includes Boston.

It requested “All available subscriber information, for the account or accounts associated with the following information, including IP address logs for account creation and for the period December 8, 2011 to December 13, 2011.” The named targets included two hashtags, two accounts, and one proper name:

That subpoena, as written, ostensibly asks for whatever identifying information Twitter has on anyone who used the hashtags #bostonpd and #d0xcak3 from 12/8/2011 to 12/14/2011, which could number in the thousands.

It’s unclear if that’s what the Boston police meant to do, or if they are unfamiliar with Twitter. It seems likely the latter, given that the @occupyboston account is a year-and-a-half old fallow account with four tweets. The quasi-official Twitter account for the Occupy Boston movement that was evicted in this time frame is @occupy_boston.

@p0isan0n purports to be a participant in Antisec, the blackhat wing of Anonymous, which has targeted the Boston Police several times in document releases that have included online logins, physical addresses, and most recently, payroll information for 40 senior officers. The subpoena may also be be related to the d0xing, or document publication, of Boston Mayor Tom Menino on December 9th, as tweeted by @youranonnews:

“Boston Mayor Tom Menino d0x’d, courtesy of @DoxCak3 — http://pastebin.com/JtFqDr7G #OccupyBoston << someone order the man a pizza, stat!”

If so, the district attorney’s office mixed up their # and @ symbols.

The subpoena also includes a request for confidentiality from the Special Prosecutions Unit, but had no actual legal gag order. Without legal orders, the request for confidentially had no more enforceability than if Assistant District Attorney Benjamin Goldberger had also asked Twitter to send him a cupcake.

It’s Twitter’s policy to forward a subpoena to its target in order to give the user a chance to fight it, unless the company is specifically gagged. It appears that @p0isan0n received a copy from Twitter and posted it to Scribd.

ACLU attorney Peter Krupp, who is representing user @p0isan0n, filed a motion to quash the subpoena on First Amendment grounds. But Thursday, the ACLU seemed to be dealt a defeat when Suffolk Superior Court Judge Carol Ball issued an impoundment order after hearing the case in whispers at the bench.

This barred anyone in the case from talking about the arguments on either side, or about why the motion to dismiss the subpoena was likely rejected. Impoundment is an extraordinary measure that can be requested by one side of a case, and is generally granted only in cases involving sensitive security issues, investigative issues, witness intimidation, or the possibility of the suspect running.

“I think none (of these reasons) are valid in this instance,” said Krupp.

For its part, the Boston Police told Boston local publication BostInno that the “Boston Police Department is investigating serious threats directed at department personnel. The department will not disclose the specific nature of the intelligence gathered relative to this matter.”

But what does it mean to subpoena a hashtag?

Krupp has a scary interpretation: “Presumably that means the IP address of anyone that uses that hashtag. It’s all IP address logs associated with that Twitter address.”

That would mean Twitter would be required to turn over the IP addresses and e-mail addresses of anyone who used the hashtag #BostonPD from December 12 to 14, a time period covering the widely followed eviction of Occupy Boston from Dewey park.

Krupp also sees a fishing expedition in the phrasing of “for the account or accounts associated with the following information”. That, he believes, could mean anyone that’s a follower of that account.

“In my view the statute… doesn’t go nearly so far in permitting an administrative subpoena to get that information,” Krupp said. “You have to go to a court and prove you’re entitled to that stuff.”

If the D.A. has this liberal interpretation of the subpoena, your humble Wired reporter is included for the incriminating act of following someone on Twitter.

Correction: The story was updated to reflect that the hearing was comprised mostly of attorneys conferring with the judge.