The practice of accessing open WiFi-systems of others without permission (so-called piggybacking) is not explicitly governed in German law. In 2007, the local court of Wuppertal held that doing so constitutes an unlawful interception of radio signals, a criminal offence prohibited by Sections 89 and 148 of the German Telecommunications Act as well as an unlawful retrieval of personal data that are generally accessible as prohibited by Sections 43 and 44 of the German Federal Data Protection Act.
The Wuppertal court's ruling has been widely criticised in German legal literature. In particular, critics noted that piggybacking doesn't usually entail obtaining any personal information concerning the owner of the WiFi-system in question nor does it entail the reception of any communications of the owner. In spite of this criticism, the ruling of the Wuppertal court was the leading German precedent on the legality of piggybacking for several years.
A decision of the same court passed in August of 2010 has now given up this legal view. In its reasoning, the court explicitly acknowledges the criticism of its ruling of 2007. This new legal view has been upheld by the regional court of Wuppertal in a ruling dated 19 October 2010 (case file number 25 Qs 10 Js 1977/08-177/10). Based on these two new precedents, piggybacking is not illegal in Germany, as long as one does not intercept any personal communications or access personal information of the WiFi-system's owner.