Written description decisions are unusually fact intensive. The court must answer (1) what exactly was invented? and (2) what exactly was claimed? Then the court must dissect the differences between the invention and the claims.
A patent has an adequate written description if it “reasonably conveys to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date.”
In Rivera v. ITC, the patent concerned a coffee brewer that could accept both “cup” and “pod” containers. A “cup” is a small, self-contained plastic cartridge. A “pod” is a small disc-shaped filter containing coffee grounds. Cups and pods hold coffee grounds differently, so it’s a bit of a trick to develop a brewer that can use both.
But Rivera took their claim on a cup-or-pod brewer and asserted that a loose-grounds-inside-a-cup apparatus infringed. This was too far for the ITC and ultimately the Federal Circuit panel:
[T]he question is whether a pod adaptor assembly intended to allow compatibility between distinct brewing systems, also supports an undisclosed configuration that eliminates a fundamental component of one of those systems (i.e., the “pod”) through integration. It does not.
I’ve long supported meaningful enforcement of the written description requirement: Inventors should get patents on what they actually invented. The written description requirement helps enforce that basic (and fair) requirement.