What makes a patent invalid due to “indefiniteness”?

June 25, 2018
Patterson Thuente IP

Although in 2014 the U.S. Supreme Court announced a standard for assessing whether patent language is fatally indefinite, the limits of the Court’s decision are still being determined. More recently, the U.S. Federal Circuit Court of Appeals provided additional guidance — and it seems to favor patentees.


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The dispute

BASF Corporation owns a patent on catalytic converter systems that work on nitrogen oxides in an exhaust gas stream. It covers a partly-dual-layer arrangement of coatings over which exhaust gas passes. One layer is described as containing a material composition “effective to catalyze” a selective catalytic reduction (SCR) of nitrogen oxides; the other is described as containing a composition “effective for catalyzing” ammonia oxidation.

BASF sued its competitor Johnson Matthey Inc. for infringement of the patent. The district court held that the “effective for catalyzing” / “effective to catalyze” language was indefinite and therefore invalidated the patent. BASF appealed to the Federal Circuit.

Clean language

In Nautilus Inc. v. Biosig Instruments, Inc., the Supreme Court held that a patent is indefinite if it fails to inform, with “reasonable certainty,” those with knowledge in the relevant field (referred to as “ordinary skilled artisans”) about the invention’s scope. The Federal Circuit applied that standard to this case, explaining that the issue was whether the patent language in question would have given such people a reasonably certain understanding of the compositions the patent covered.

The Court of Appeals began its analysis by faulting the district court for focusing on the functional nature of the BASF patent’s language. The Nautilus standard, it said, doesn’t exclude claim language that identifies a product by what it does. Instead, what’s required is a context-specific inquiry into whether the particular functional language actually provides the necessary reasonable certainty.

The appellate court also criticized the district court’s reliance on the lack of language identifying a minimum level of function needed for a composition to qualify as “effective.” The lower court said this absence meant ordinary skilled artisans couldn’t determine which materials qualified as patented compositions.

According to the Federal Circuit, though, other language in the patent made clear that it’s the partly-dual-layer arrangement of the catalysts, not the selection of particular catalysts, which purportedly rendered the invention an advance over existing inventions. The context of the language at issue — that is, other language in the patent — let the public know that any known catalysts could be used so long as they play their described roles.

In addition, other language in the patent provided examples of material compositions that are “effective” to catalyze an SCR reduction of the nitrogen oxide and ammonia oxidation. Such language also disclosed the chemical reactions that define the SCR function and ammonia oxidation function. And it illustrated — with figures, tables and accompanying descriptions — how the purportedly novel arrangement of the catalysts results in improvements.

Notably, the appellate court addressed a footnote in the district court’s opinion that cited Johnson Matthey’s expert’s assertion that a practically limitless number of materials could perform the required catalysis. The lower court treated that scope as indicating that the language in question failed to sufficiently identify the material compositions. But, the court said, the inference of indefiniteness simply from the scope finding was legally incorrect because “breadth is not indefiniteness.”

Clearing the air

The court’s ruling provides assurance that a patent that uses functional language won’t be held invalid simply for that reason. If it informs ordinary skilled artisans about the scope of the covered invention with reasonable certainty, the patent shouldn’t fail due to indefiniteness. •

BASF Corp. v. Johnson Matthey Inc., No. 16-1770, Nov. 20, 2017, Fed. Cir.

Nautilus, Inc. v. Biosig Instruments, Inc., No. 13-369, June 2, 2014, S.Ct.

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