The German competition law may apply to foreign companies as well when the respective company advertises using the online domain name .de.
If a legal entity has its headquarters in Switzerland is not relevant, according to the German Supreme Court. If the content of the advertising messages is directed toward a German audience, the German legal system applies. Therefore, if a Swiss business used a domain with the .de extension, it is considered that the statements are addressed towards a German audience and the acquisition process takes place in Germany as well. Therefore, the company is a subject of the German competition legislation.
Source: Berlin Court of Appeal, ruling Az 5U 20/14 from 27.11.12.