The process of claim construction—interpreting the meaning of the words used in a patent claim—can be confusing at the best of times. At its worst, as in the Federal Circuit’s Dupont v. Unifrax decision this week, it most closely resembles an exchange from Lewis Carroll’s “Through the Looking Glass.”
“I don’t know what you mean by ‘glory’,” Alice said.
Humpty Dumpty smiled contemptuously. “Of course you don’t—till I tell you. I meant ‘there’s a nice knock-down argument for you !’”
“But ‘glory’ doesn’t mean ‘a nice knock-down argument,’” Alice objected.
“When I use a word,” Humpty Dumpty said in rather a scornful tone, “it means just what I choose it to mean — neither more nor less.”
“The question is,” said Alice, “whether you can make words mean so many different things.”
“The question is,” said Humpty Dumpty, “which is to be master — that’s all.”
In Unifrax, the Federal Circuit showed a determination to be the master of the meaning of words—even if it requires them to make interpretations as counter-intuitive as Humpty Dumpty’s take on ‘glory.’
When 100% Isn’t 100%
Everyone is familiar with what “100%” means. It’s on juice boxes, telling us that the product is nothing but juice. It’s on clothing, telling us that our shirt is made of nothing but cotton. We even have a shorthand emoji for it—💯.
We use “100%” whenever we understand that something is composed entirely of one thing, with nothing else.
But according to the Federal Circuit, the meaning of 100% is something totally different.
Dupont v. Unifrax
Dupont owns a patent on a type of laminated flame barrier, used to protect aircraft fuselages from fires. Dupont’s patent specifically states that it covers a multilayer laminate. In addition to a film layer and an adhesive layer, neither of which is at issue here, the laminate also includes:
(iii) an inorganic refractory layer; wherein the inorganic refractory layer of (iii) comprises platelets in an amount of 100% by weight with a dry areal weight of 15 to 50 gsm…U.S. Pat. No. 8,607,926 (emphasis added).
100% by weight is fairly clear. 100% of the layer, when dry, must be platelets (and must weigh from 15-50 gsm). But that language isn’t clear-cut if you’re the Federal Circuit. According to two CAFC judges1, instead of the plain meaning of “100% by weight”, what the patentee actually meant by this was “[t]here is no carrier material such as resin, adhesive, cloth, or paper in addition to the inorganic platelets. There may be some residual dispersant arising from incomplete drying of the platelet dispersion.” They did this based on various brief passages in the specification which mention other embodiments that aren’t 100% platelets by weight and a related patent, but ignore portions of the specification that contradict this and the patentees’ amendment during prosecution to get around prior art that had a platelet layer, but not a 100% platelet layer.
According to the Federal Circuit, reading a limitation from the specification into the claims is “one of the cardinal sins of patent law.” But here, the Federal Circuit did exactly that, taking a clear term—“100% by weight”—and reading in limits from the specification to stretch the meaning out to mean only that it’s 100% of the platelet material and 0% carrier, but we can safely ignore things that are neither platelet material nor carrier.
So a layer which is composed of 80% platelets and 20% dispersant by weight? That, according to the Federal Circuit, meets a limitation which—on the patent’s face—says “100% by weight.”
CAFC to the Public: A Word Means “Just What I Choose It To Mean”
Patents are supposed to “give notice to the public of the limits of the patent monopoly.” People should be able to look at the claims and say “I can do this, but not this.” But if the meaning of a claim is unclear or ambiguous, the scope of the patent monopoly becomes unclear. And when the scope of the patent monopoly is unclear, it creates a “zone of uncertainty which enterprise and experimentation may enter only at the risk of infringement claims.” This is a serious enough problem when a claim term is simply unclear, creating infringement risks for companies that innovate in areas like software where unclear claims are particularly common.
How much worse will the problem be if a company can’t even be sure that “100%” means “100%”?
- Judge O’Malley dissented, believing that the limitation was quite clear in meaning exactly what it says—100% by weight. ↵