Siddle purchased a quantity of fireworks from Red Devil Fireworks Co. The sale was illegal, however, because Siddle did not have a license to make the purchase, which the seller knew because it had been so informed by the attorney general of the state. Siddle did not pay for the fireworks, and Red Devil sued him. He defended on the ground that the contract could not be enforced because it was illegal. Was the defense valid? [Red Devil Fireworks Co. v Siddle, 648 P2d 468 (Wash App)]