Facebook may prevent its users from using fake names, a German court said on Thursday, overturning a previous order from the Hamburg data protection authority. Facebook has been arguing that its real-name policy ensures people know who they are sharing and connecting with and protects them from abuse.

The Hamburg data protection authority said last July that Facebook could not unilaterally change users' chosen usernames to their real names, nor could it ask them for official identification.

The Hamburg Administrative Court on Thursday ruled Facebook did not have to implement the order since its European headquarters are in Ireland it should therefore only have to abide by Irish law.

The applicable law is that "of the European Union member state that is most closely related to the data processing at stake," the court said. "As to the real-name rule, this is Facebook's Ireland branch."

The order was based on a complaint by a user who'd sought to prevent her private Facebook account from being used by people wishing to contact her about business matters. Facebook changed the profile to her real name against her will and asked for a digital copy of her identity card or passport.

Yesterday, Germany's antitrust regulator said it's examining whether Facebook abused its possible market dominance by forcing customers to agree to terms allowing the use of their data.