Nordenfelt v Maxim Nordenfelt Guns and Ammunition Co Ltd [1894] AC 535 is a 19th-century English case decided by the House of Lords. The dispute was about restraint of trade, and the judgment declares when such a restraint (which is prima facie void) may become valid. The case also established the "Blue pencil doctrine" as a method for deciding whether contractual obligations can be partially enforced when the obligation as drafted in the contract has an element of illegality.