"If you post a tweet, just like if you scream it out the window, there is no reasonable expectation of privacy," Sciarrino wrote. "There is no proprietary interest in your tweets, which you have now gifted to the world."

Harris' Fourth Amendment rights that protect against unlawful search and seizure do not apply because there was "no physical intrusion of the defendant's tweets," Sciarrino wrote.

Prosecutors want Harris' tweets between Sept. 15 and Dec. 31, 2011, in order to refute an "anticipated defense" that police led or escorted him and hundreds of others onto the bridge's road, according to court documents.

Twitter said in a statement that it was disappointed by the ruling and considering its options.

"Twitter's Terms of Service have long made it absolutely clear that its users own their content," the company said. "We continue to have a steadfast commitment to our users and their rights."