Permutit Co. v. Graver Corp.

Background

A company that owned a patent for an apparatus using zeolites to soften water sued a rival manufacturer in federal court, seeking to stop alleged copying of two patent claims. The patent covered a filter in which zeolites could be used and regenerated for continuous softening. Lower courts in Illinois held the two claims invalid, and the rival’s structures were found not to infringe Claim 5; certiorari was granted because other circuits had reached different results.

Reasoning

The central question was whether the patent actually described and claimed the features the owner later relied on, especially the so-called “free” zeolite bed that allows grains to rise and reform. The Court found the specification and claims did not describe that free bed or the need for a rising space, and that the drawing could not supply the missing written description required by statute. The Court also rejected the idea that merely placing a drain at the bottom of the casing was an inventive step. For those reasons, the Court affirmed the invalidity of the challenged claims and agreed that the defendant’s current design did not infringe Claim 5.

Real world impact

Because the patent claims were held invalid, the patent owner cannot use this patent to enjoin the rival’s use of the described filter designs. The decision emphasizes that a drawing alone cannot replace a clear written description of the claimed invention. The ruling resolves the dispute before the Court and leaves other manufacturers freer to use similar zeolite filter features unless a valid patent claim actually describes them.