There is a case before the Bundesgerichtshof (Federal Court of Justice) in Karlsruhe in Germany, over the right to exclusively use a 4×4 square design for chocolate slabs. German chocolatier Ritter Sport introduced it way back in 1932. In 2010 Swiss company Milka started using it as well.
Now Ritter Sport alleges that Milka violates its patent that had been registered in 1993.
Update Thu 7/23: A ruling in favor of Ritter Sport came down from the Bundesgerichtshof. Milka will no longer be allowed to copy the square design of the Ritter chocolate slabs.