Mast, Foos & Co. v. Stover Manufacturing Co.

Background

An inventor held a patent (the Martin patent) for using an internal-toothed wheel meshing with an external pinion in a windmill to convert the wheel’s rotation into the up-and-down motion of a pump shaft. The inventor sued manufacturers and earlier appeals courts split on whether that use was new. The current appeals court declined to follow an earlier decision from another circuit and dismissed the inventor’s bill, and the matter reached this Court for review.

Reasoning

The Court examined prior devices and many earlier patents showing internal-toothed wheels and similar gear combinations used in other machines and in windmills for different purposes. It explained that courts should give respectful weight to other courts’ rulings (comity), but that comity does not bind judges who must decide cases based on their own view of the law and facts. Looking at the state of the art, the Court concluded Martin did not create a new device or new function; he applied an existing gear combination to a slightly different use. The Court held that this transfer was the kind of step an ordinary skilled mechanic could make, not an act of invention, and therefore the patent was not valid.

Real world impact

The Court affirmed the appeals court’s dismissal and confirmed that weak patent claims based on obvious transfers of old gears can be thrown out. It also endorsed that an appellate court may dismiss plainly meritless patent suits without a full evidentiary hearing. Manufacturers using long-established gear arrangements and patentees asserting incremental uses are most directly affected.