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Patentee Bears the Burden of Establishing Non-Enablement of Allegedly Anticipatory Prior Art Reference


In Impax Laboratories, Inc. v. Aventis Pharmaceuticals Inc. (No. 07-1513; October 3, 2008), the Federal Circuit explains that anticipation requires that a prior art reference enable one of ordinary skill to make the claimed invention without undue experimentation, and that the patentee has the burden of establishing non-enablement of the asserted prior art reference.

Impax brought a declaratory judgment action and alleged, among other things, that claims of a patent owned by defendant Aventis were anticipated by a prior art patent. Aventis' patent claims a method for treating mammals with amyotrophic lateral sclerosis (ALS) using riluzole. Following a remand by the Federal Circuit of an earlier appeal in the case, the district court made specific factual findings related to the question of whether the alleged prior art enables one of ordinary skill to treat ALS with riluzole.

In affirming the district court's ultimate findings of non-enablement and non-anticipation by the prior art reference, the Federal Circuit finds no error in the district court's factual finding and analysis. In particular, the Court holds that the district court properly placed the burden of establishing non-enablement of the prior art patent on the patentee and that the patentee met that burden. The Federal Circuit also cites with approval specific facts found by the district court, including that (1) the alleged prior art patent disclosed a "formula I" that encompassed hundreds or thousands of compounds and disclosed several diseases, but that nothing in the prior art patent would direct one of ordinary skill to recognize that riluzole could be used to treat ALS; (2) while formula I encompassed riluzole, the prior art patent explicitly excluded riluzole from the scope of the invention; (3) the dosage guidelines in the prior art patent were broad, were not specific to any of the hundreds of formula I compounds or to any of the listed diseases, and were tied to the compounds of the invention; and (4) the prior art patent disclosed no working examples.


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Mark Supko
Partner – Washington, D.C.
Phone: +1 202.624.2734