German law protects sharp criticism, but not Schmähkritik, abusive criticism. The Federal Constitutional Court defines the line, as German Wikipedia quotes it. A disparaging statement becomes abusive only wenn in ihr nicht mehr die Auseinandersetzung in der Sache, sondern die Diffamierung der Person im Vordergrund steht, when it is no longer about the matter, and the defamation of the person comes to the fore.