Aventis Prevails over Impax in Riluzole Dispute

    By Robert Dailey —

On remand from the Federal Circuit (see "Impax Labs., Inc. v. Aventis Pharm. Inc. (Fed. Cir. 2006)"), the District Court found that U.S. Pat. No. 5,527,814 is not anticipated by the prior art.  Particularly, the Court found that the anticipating reference cited by Impax does not enable one of skill in the art to use rizulole to treat amyotrophic lateral sclerosis (ALS).

The District Court had already reached this conclusion once, finding that the prior art failed to show that rizulole would be effective for treating ALS.  At the time of the Court’s initial decision, this finding was probably sufficient to demonstrate that the anticipating reference was not enabled.

But between the date of the District Court’s initial opinion and the date of the appeal, the Federal Circuit articulated a more nuanced approach to determining whether anticipating prior art is enabled.  See Novo Nordisk Pharms. v. Bio-Tech. Gen. Corp., 424 F.3d 1347 (Fed. Cir. 2005); Rasmusson v. SmithKline Beecham, 413 F.3d 1318 (Fed. Cir. 2005).  Under the more nuanced approach, the District Court cannot find a lack of enablement simply based on the anticipating reference’s failure to show effectiveness.  According to the Federal Circuit, effectiveness is more relevant to questions of utility.  To determine lack of enablement, the fact-finder must look to whether the anticipating reference teaches one of ordinary skill in the art to practice the invention without undue experimentation, where undue experimentation is evaluated in light of the eight Wands factors.

In most situations, this distinction probably makes little difference.  In fact, Judge Rader dissented in part from the Federal Circuit opinion because he believed that the District Court’s factual findings supported the validity of the Aventis patent under the old standard as well as the new standard.  But the majority preferred to remand the case to the District Court for re-evaluation in light of Rasmusson.

In last week’s opinion, the District Court found that the anticipating prior art cited by Impax still lacked enablement.  While Rasmusson has changed the formal process for evaluating enablement, it probably will have little outcome-determinative effect in most cases.  Commentators have long recognized that utility and enablement are related.  Though the two doctrines rely on different legal tests, evidence that demonstrates lack of utility will often also demonstrate lack of enablement.  But in the context of anticipation, the federal courts have held that enablement, and not utility, is the relevant inquiry for determining whether an anticipating reference precludes patentability.

We may ponder, though, whether this nuanced distinction carries much of a punch.  After all, enablement and utility are both malleable concepts.  The former is judged against an eight-factor balancing test, while the latter requires one to wade through the shifting sands of Brenner v. Manson, In re Brana, and In re Fisher.  Moreover, is there a doctrinally sound reason why we look to enablement but not to utility in evaluating the value of an anticipating reference?  In looking back at old CCPA cases, see, e.g., In re Hoeksema, 399 F.2d 269 (C.C.P.A. 1968), patent courts appear to have applied this "enabling disclosure" requirement in a flexible manner that dually encompassed considerations of both enablement and utility.  And especially when the claims-in-suit are method claims, wouldn’t we want to consider whether the anticipating reference failed to demonstrate the utility of the method?  After all, how can one of skill in the art make and use something that is not useful?

Impax Labs., Inc. v. Aventis Pharm. Inc., No. 02-581-JJF (D. Del. 2007)
Opinion by District Judge Farnan

Robert Dailey, Ph.D., is a physical chemist and regular Patent Docs
contributor.  Dr. Dailey, who recently completed his studies at the
University of North Carolina School of Law and passed the patent
registration exam, will be joining MBHB this fall.

Additional Disclaimer:  MBHB represented Aventis in the above litigation.  To the extent that this case summary contains any opinions, the opinions would be of Dr. Dailey and not Aventis or MBHB.