A substantial number of patents tested in court for validity are invalidated. If a similar portion of all patents was deemed invalid in hypothetical validity tests, then this would indicate a seriously flawed patent system due to restrictions unduly imposed by these erroneously granted patents on users and follow-on innovators. [---] Empirically, we focus on Germany, where revocation proceedings are separate from infringement suits and where, in court decisions during the period of 2010–2012, 45% of patents were determined to be fully invalid and 33% to be partially invalid. [---]