Impax Laboratories v. Aventis Pharmaceuticals

Impax Laboratories, Inc. v. Aventis Pharmaceuticals Inc., 545 F.3d 1312 (2008)

- '814 patent relates to the use of riluzole to treat amyotrophic lateral sclerosis (ALS or Lou Gehrig's diease)
- Aventis own the '814 patent with the trade name of RILUTEK
- Impax filed with the FDA an ANDA seeking approval to market generic riluzole tablets

Procedural History:
- Impax sued Aventis for a declaratory judgment that Impax did not infringe the '814 patent
- Impax claimed the '814 patent was invalid and unenforceable
- At a bench trial, the district court rule against Impax and determined that the '814 patent was not proven to be unenforceable
- No finding of inequitable conduct or claims anticipated by prior art ('940 patent)
- Impax appealed
- Court of Appeals affirmed-in-part, vacated-in-part, and remanded to the district court
- District court determined that the '940 patent does not enable and therefore does not anticipate claims 1-5 of the '814 patent
- Impax appealed the remand to the Court of Appeals again

- Does the prior art ('940 patent) reference enable one of ordinary skill in the art to make the invention without undue experimentation?

- An issued patent enjoys a presumption of validity
- The party challenging patent validity has the burden to prove its case with clear and convincing evidence
- Under the clear error standard, the district court's findings will not be overturned in the absense of a definite and firm conviction that a mistake has been made

(1) The lower court found that if the '940 patent was not enabling prior art and would require excessive experimentation in order to practice the invention
- nothing in the '940 patent would lead one skilled in the art to use riluzole to treat ALS
- mere mention of riluzole is not sufficient
- the disclosure did not teach proper treatment
(2) The lower court properly placed burden of proving nonenablement on the patentee. At which point, the patentee met that burden with persuasive evidence that the '940 patent did not enable claims 105 of the '814 patent
- the lower court found that the record showed sufficient evidence to overcome teh presumption of enablement

- The lower court properly applied the enablement standard and correctly determined that the '940 patent is not an enabling prior art reference and that it does not anticipate claims 1-5 of the '814 patent
- Affirmed
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