Occupy Wall Street protestor Malcolm Harris may be inciting a very different kind of revolution than the one he intended: a fight between Twitter and the Manhattan District Attorney's office. Twitter today filed a motion to quash a subpoena by the DA's office requesting "any and all user information" related to Harris's account; among other arguments, the social networking service says that being forced to turn over Harris's information would constitute an unreasonable search in violation of the Fourth Amendment.

Harris was arrested on October 1st of last year when he marched on the Brooklyn Bridge as part of an Occupy protest. As part of the proceedings against him, the Manhattan DA subpoenaed Twitter, requesting "any and all user information" connected to Harris's @destructuremal Twitter account between September 15 and December 31, 2011. Harris himself tried to fight that request, but a judge ruled in January that he didn't have the proper standing to prevent the DA from subpoenaing Twitter because the Twitter terms of service give the company a worldwide license to whatever Harris uploads to the service. (Twitter needs that license to move content around on its servers and display Tweets and images; Google, Apple, Microsoft and others all have similar provisions for their online services.)

Twitter argues that that license shouldn't apply in Harris's case because the license also specifically says that users retain the rights to their content, and that the federal Stored Communication Act specifically allows users to challenge requests for their information. According to Twitter, the court's decision to deny Harris an opportunity to fight the DA's subpoena "imposes a new and overwhelming burden on Twitter to fight for its users' rights," since it will have to either always give up information or get directly involved in every Twitter user's defense when there's a request for tweets.

If the Order stands, Twitter will be put in the untenable position of either providing user communications and account information in response to all subpoenas or attempting to vindicate its users' rights by moving to quash these subpoenas itself — even though Twitter will often know little or nothing about the underlying facts necessary to support their users' argument that the subpoenas may be improper.

Twitter also argues that subpoena violates the Fourth Amendment's prohibition since the police don't have a search warrant — searches for information under the Stored Communication Act still require a warrant, and the Supreme Court recently ruled that searching even seemingly-public activity requires a warrant in the landmark Jones GPS-tracking case.

If the Fourth Amendment's warrant requirement applies merely to surveillance of one's location in public areas for 28 days, it also applies to the District Attorney's effort to force Twitter to produce over three months worth of a citizen's substantive communications, regardless of whether the government alleges those communications are public or private.

That's a bold line for Twitter to take, but it makes sense: the company can't afford to sit between every single defendant who uses Twitter and the law enforcement authorities who might want to look at their accounts. More importantly, the company needs to reassure users that it's standing up for them in order to protect the vibrancy and honesty of Twitter itself. Whether the court agrees is another matter — we'll see what happens.