Twitter has joined the fight to protect the privacy of an Occupy Wall Street protester who’s resisting efforts by the New York County District Attorney to subpoena tweets he published last fall.

This tug of war for information seems overcomplicated in light of a simple truth: The information the prosecutors are requesting, as with most of the data users post on Twitter, is already public. After all, Twitter reminds us in its Terms of Service: “What you say on Twitter may be viewed all around the world instantly. You are what you Tweet!”

But what happens if a user deletes a tweet? Can Twitter be forced to provide it? And it can be hard to dig through millions of tweets. Does Twitter have to help law enforcement look?

Twitter’s motion, filed Monday, seeks to quash a court order requiring it to provide 107 days of tweets last fall from Malcolm Harris, who was charged with disorderly conduct in October during the OWS protests. Twitter’s legal counsel Benjamin Lee tweeted Tuesday, “Yesterday we filed a motion in NYC to defend a user's voice."

But Twitter’s actions may have been less about protecting Harris and more about defending itself from legal requests for data. Harris had previously filed a motion to quash the subpoena, but the judge had denied his request, arguing Twitter owns his tweets, not him.

Twitter’s motion rejects that idea, saying the data belongs to Harris. As its Terms of Service state: “You are responsible for your use of the Services, for any Content you post to the Services, and for any consequences thereof.” Twitter also argues that handing over data would violate the Fourth Amendment’s protections of searches without warrant, even when the government requests information about “allegedly public information.”

But the portrayal of Twitter as an advocate for privacy seems at odds with its purpose, which is to disseminate information to the public.

While the lawyers argue, how’s Harris taking the news?

“I'm thinking this bodes well for my request currently in to Twitter PR to borrow one of their giant blue birds and ride it into court,” he tweeted.

(Kirsten Salyer is the social media editor for Bloomberg View. Follow her on Twitter.)

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