A spokeswoman for Vance declined to comment on Twitter's appeal.

The American Civil Liberties Union applauded Twitter for appealing the ruling.

U.S. residents "have the right to speak freely on the Internet, safe in the knowledge that the government cannot obtain information about our communications or our private information unless law enforcement ... obtains a warrant showing probable cause," Aden Fine, a senior staff attorney with the ACLU, . "The DA didn't do that here. Instead, it has tried to avoid these constitutional hurdles by issuing a mere subpoena for Harris's Twitter information."

The information Vance has sought includes private subscriber information, including Harris' IP addresses, Fine wrote. "By denying Twitter's and Harris' challenge, the court held that the government can access this wealth of sensitive personal information without satisfying basic constitutional protections," he wrote. "That isn't right."

The IDG News Service