Now this is a really interesting legal case. Facebook has a marketing and advertising business established as a separate legal entity in Germany. In December 2012, the Schleswig DPA issued orders against Facebook Inc. in the U.S. and Facebook Ltd. in Ireland, in which the DPA demanded that Facebook allow its German users to use pseudonyms.
So which law applies? Germany, Ireland, or US? In the end Germany lost. It was decided that the Irish DPU laws applied. The ruling stated that it was not considered a sufficient presence to warrant the application of German data protection law.