When a “wherein” clause in a method claim lends patentable weight to the claim, the clause is limiting, and is not simply the expression of an intended result.

The alleged infringers in a pharmaceutical patent case appealed the district court’s grant of a preliminary injunction against a generic version of the patentee’s ophthalmic drug, Combigan®. The patents generally relate to a method of treating a patient using a combination of two active ingredients. Notably, the claims include certain “wherein” clauses that recite the ability to reduce the frequency of the administrations of the combination from three times down to twice daily, as compared to monotherapy, and without loss of efficacy. The district court had held that the “wherein” clauses are limiting because they are not merely the expression of an intended result of a process step.

The Federal Circuit affirmed, finding that the wherein clauses recite benefits from the specification that were material to patentability, and which were relied upon during prosecution to overcome rejections. The examiner also explicitly relied on the recited benefits when allowing the claims. The parties did not dispute that the grant of preliminary injunction rises or falls on the claim construction. Accordingly, because the claim construction was affirmed, so was the grant of a preliminary injunction. 

Chief Judge Prost concurred with the reasoning, but added the view that the accused infringer had not shown that the “wherein” clauses were in fact simply the inherent result of the claimed method. Judge Prost explained that the plain language of the claim compelled the result that the clauses are indeed limiting.