Duramed Pharmaceutical v. Paddock Laboratories (CAFC 2010-1419) precedential; Judges Lourie (author), Gajarsa, Dyk

'638 was granted over otherwise obviousness by adding the limitation: "a moisture barrier coating comprising ethylcellulose." It was common at the time to grant patents for niggling improvements like this, back when the patent office was granting patents like handing out candy on Halloween. Which is to say that the patent should be invalid under the Obzilla regime straight-up, but Paddock decided to go the rifle-shot approach by arguing non-infringement, with an Obzilla backing.

Paddock's proposed generic product uses a polyvinyl alcohol ("PVA") MBC [moisture barrier coating], marketed as Opadry AMB. Paddock moved for summary judgment of noninfringement, arguing that Duramed was barred by amendment-based prosecution history estoppel from alleging that PVA met the "moisture barrier coating comprising ethylcellulose" limitation of the asserted claims.

Paddock showed that PVA was a well-known prior art technique (specifically, "the Colorcon PCT") to moisture-proof a pill.

The district court first held that Duramed's amendment adding the ethylcellulose limitation was substantially related to patentability and narrowed the scope of the asserted claims, thus triggering the presumption under Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 344 F.3d 1359, 1366-67 (Fed. Cir. 2003) (en banc) ("Festo IX"), that Duramed had surrendered all territory between the original and amended claim scope. Duramed, 715 F. Supp. 2d at 559-60.

The district court then held that Duramed had failed to rebut the Festo presumption based on an argument of, inter alia, the unforeseeability of the use of PVA as an MBC in a pharmaceutical formulation. Id. at 560.

On appeal, the same song with more lyrics -

Under the doctrine of the equivalents, "a product or process that does not literally infringe . . . the express terms of a patent claim may nonetheless be found to infringe if there is 'equivalence' between the elements of the accused product or process and the claimed elements of the patented invention." Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 21 (1997) (citing Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 609 (1950)). However, the doctrine of prosecution history estoppel prevents a patent owner from recapturing through the doctrine of equivalents subject matter surrendered to acquire the patent. See Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 734 (2002) ("Festo VIII").

Because during prosecution Duramed narrowed the scope of the '638 patent's claims in response to a prior art rejection, a presumption of prosecution history estoppel applies. See Festo IX, 344 F.3d at 1366-67. Nonetheless, Duramed may rebut that presumption by showing, inter alia, the "alleged equivalent would have been 'unforeseeable at the time of the amendment and thus beyond a fair interpretation of what was surrendered.'" Id. at 1369 (quoting Festo VIII, 535 U.S. at 738). "[A]n alternative is foreseeable if it is disclosed in the pertinent prior art in the field of the invention. In other words, an alternative is foreseeable if it is known in the field of the invention as reflected in the claim scope before amendment." Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 493 F.3d 1368, 1379 (Fed. Cir. 2007) ("Festo X"). Foreseeability is a question of law based on underlying issues of fact. Id. at 1375.

We agree with Paddock that Duramed failed to rebut the presumption of prosecution history estoppel based on unforeseeability. We first note that, to the extent that Duramed argues that foreseeability requires that PVA must have been known as an MBC for use with conjugated estrogens, we have previously rejected such a restrictive definition of the field of invention. See Schwarz Pharma, Inc. v. Paddock Labs., Inc., 504 F.3d 1371, 1377 (Fed. Cir. 2007). As we spelled out in Schwarz, when the language of both original and issued claims begins with the words "[a] pharmaceutical composition," that language defines the field of the invention for purposes of determining foreseeability. Id. Accordingly, PVA MBCs need only to have been known in the field of pharmaceutical compositions as of the time of Duramed's narrowing amendment, see Festo X, 493 F.3d at 1379, which we hold that the Colorcon PCT establishes as a matter of law.

Affirmed.