Adolphe Sax was sued over patents several times. When Sax’s original patent expired, several instrument makers applied for patents of the changes they’d made to Adolphe’s saxophone. A few years later Adolphe Sax renewed his original patent with changes. This prompted some instrument makers to sue for patent infringement or to have Adolphe’s patent ruled illegitimate. The bottom line is that Adolphe's competition was trying to have his patents revoked. In the end, Adolphe Sax won, and his patents were ruled perfectly legal.