Benjamin Robbins Curtis, Kinsman v. Parkhurst — Opinion of the Court
“ The invalidity of the patent does not render the sales of the machine illegal, so as to taint with illegality the obligation of the defendants to account. Even where money has been received, either by an agent or a joint owner, by force of a contract which was illegal, the agent or joint owner cannot protect himself from accounting for what was so received, by setting up the illegality of the transaction in which it was paid to him. ”
