Schinzing invented and patented a wheel-chair washing machine. Mid-States Stainless agreed to sell the product and pay royalties. After termination of the agreement Schinzing sued for breach of contract in state court. Mid-States Stainless removed to federal court by asserting a counterclaim of patent invalidity. The Eight circuit adopted the Federal Circuit precedent and held that "an element-by-element comparison of the ’375 patent to: (1) the aspects of the modified washer that the evidence showed were proposed by the students; (2) the device shown in the student demonstration; and (3) the device described in the student report" were indispensible findings of fact not made by the district court.