Twitter is fighting a federal magistrate judge’s order that it provide identifying information about an anonymous account to lawyers who want to sue the user for copyright infringement.

A motion filed late Friday by Twitter’s lawyers at Perkins Coie says U.S. Magistrate Judge Donna M. Ryu errored when she placed the burden of establishing fair use entirely on the anonymous user. It asks for a U.S. District Court judge to vacate Ryu’s Dec. 29 order that granted Bayside Advisory LLC’s motion to compel and rejected Twitter’s motion to quash. Ryu had given the company 10 days to comply.

U.S. Magistrate Judge Donna M. Ryu.