Using a Patent on a Device Accused of Infringement Under Doctrine of Equivalents | November 2012

Infringement under the doctrine of equivalents requires that the differences between the device claimed in the asserted patent and the device accused of infringing the patent should be insubstantial.[4] In a number of cases before the 1990's the argument that an accused device did not infringe under the doctrine of equivalents if it was covered by its own patent was rejected.[5] The fact of the patenting alone did not show that the differences between the patented and accused products were not insubstantial. In one of these cases, Atlas Powder Co. v. E.I. Du Pont De Nemours & Col., 750 F.2d 1569 (Fed. Cir. 1984), the court indicated that if an accused product was patented because of unexpected results “the unexpected results might prompt a finding of no equivalence” on the basis that the results were substantially different from the results achieved by the product patented by the asserted patent. Atlas Powder at 1580 n.3. In a similar vein the courts had considered whether persons reasonably skilled in the art would have known of the interchangeability of a part in the accused device with one in the claimed device as a useful guide in assessing the equivalency between a claimed and an accused device.[6] Thus the ground was laid for finding that, under the right circumstances, and using principles of obviousness, the patenting of an accused device could demonstrate that differences between the claimed and accused devices were substantial so as to defeat a finding of equivalency.

In 1994 the Federal Circuit in Hoganas AB, v Dresser Indus., Inc., 9 F.3d 948 (Fed. Cir. 1994) affirmed the district court's grant of summary judgment of non-infringement, both literally and under the doctrine of equivalents. The court noted that the Patent Office had granted a patent to the accused infringer covering the accused product with knowledge of the asserted patent, and thus "must have considered the accused product to be nonobvious with respect to the patented composition." Id. at 954. The Court referenced the footnote in Atlas referred to above, stating that "a finding of 'unexpected results' was tantamount to a finding of obviousness." Id. n.28. Four decisions of the Federal Circuit touching on this issue followed in 1996. In National Presto Indus. v. The West Bend Co., 76 F.3d 1185 (Fed. Cir. 1996) the court confirmed the principle that the separate patentability of the accused device is relevant to the issue of whether there may be equivalency between a claimed device and an accused device, pointing out that the patent and its subject matter were not of record at the trial, but noting that the asserted patent had been cited in the patent on the accused device. Id. at 1191. In Roton Barrier, Inc., v. The Stanley Works, 79 F.3d 1112 (Fed. Cir. 1996) the court found that there was no infringement under the doctrine of equivalents because of substantial differences between the claimed and accused devices. Judge Nies, adding views in a concurring opinion, found it significant that the accused infringer obtained its own patent on the accused device over the asserted patent, observing that "a substitution in a patented invention cannot be both non obvious and insubstantial." Id. at 1128. Then in Hoechst Celanese Corp. v. BP Chem. Ltd. 78 F.3d 1575 (Fed. Cir. 1996), two weeks later, the court, in affirming a finding of literal infringement, reaffirmed the basic principle that the existence of a separate patent on the accused device or process is not presumptive evidence of non-infringement. Finally, in Zygo Corp., v. Wyko Corp., 79 F.3d 1563 (Fed. Cir. 1996) the court, in a judgment delivered by Judge Nies, found that the accused system differed substantially from the patented system and thus did not infringe, referring to the fact that the accused system was separately patented by a patent that cited the asserted patent. The court, picking up Judge Nies's theme from Roton Barrier, found the patent covering the accused system to be presumed non obvious in view of the asserted patent, and that the non-obviousness was relevant to the issue of whether the change in the accused system was substantial in assessing equivalency. Id. at 1570.

The principle espoused by Judge Nies in Roton Barrier, that a change to a patented invention cannot be both non obvious and insubstantially different, was confirmed as a 'strong argument' by the court in Festo Corp., v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 493 F.3d 1368, 1380 (Fed. Cir. 2007). However, the court recently balked at finding conversely that "equivalence is tantamount to obviousness" where a patented product is found to infringe under the doctrine of equivalents (Judge Prost dissenting and supporting the express incorporation of Judge Nies's principle into the equivalence analysis). Siemens Med. Solutions v. Saint-Gobain Ceramics & Plastics, Inc., 637 F.3d 1269, 1282 (Fed. Cir. 2011).

Recent district court cases suggest that, consistent with the fact patterns in the 1996 Federal Circuit cases, a patent covering an accused device will be admitted as one factor relevant to the issue of whether differences between the patent and accused devices are substantial, but usually only if there is some basis for arguing that the Patent Office issued the patent over the asserted patent, and thus de facto determined the patent to be non-obvious over the asserted patent.Interstore Transfer Sys., Ltd., v. Hanger Management, Inc., 1997 WL 106109 (N.D. Ill.) (patent on accused device cited the asserted patent but was excluded in absence from the record of the file history); Arlaine & Gina Rockey, Inc., v. Cordis Corp., 2004 WL 5504978 (S.D. Fla.) (patents on accused devices did not cite the asserted patent but were admitted as relevant to equivalency); Engineered Prods. Co., v. Donaldson Co., Inc., 313 F.Supp.2d 951 (N.D. Iowa 2004) (patent on accused device cited asserted patent and was not excluded as irrelevant even though the patentee argued there was little in the prosecution history to show the Patent Office had directed itself to anything pertinent to substantial differences between the patents); and Hochstein v Microsoft Corp., 2009 WL 2022815 (E.D. Mich.) (the court emphasized the non-obvious rationale for considering a patent on the accused device and excluded such a patent because it did not cite the asserted patent).

A party with a patented product accused of infringing another patent under the doctrine of equivalence should check the prosecution file histories of its own patents carefully for any evidence that may suggest that the Patent Office considered the asserted patent, or any related patents, when allowing any patent covering the accused device. Such evidence should be produced, along with the patents, in support of the argument that the differences between the patented device and the accused device are not insubstantial. The absence of supporting evidence demonstrating non-obviousness over the asserted patent increases the chance that a patent on the accused device will be excluded as irrelevant and prejudicial under the general principle that such a patent is no defense to infringement.

Footnotes:

1. See e.g. Bio-Tech. Gen. Corp. v. Genentech, Inc., 80 F.3d 1553, 1559 (Fed. Cir. 1996), Glaxo Wellcome, Inc. v. Andrx Pharm. Inc., 344 F.3d 1226, 1233 (Fed. Cir. 2003)

2. Hoechst Celanese Corp. v. BP Chem. Ltd. 78 F.3d 1575, 1582 (Fed. Cir. 1996).

3. Siemens Med. Solutions v. Saint-Gobain Ceramics & Plastics, Inc., 637 F.3d 1269, 1282-1283 (Fed. Cir. 2011).

4. Hilton Davis Chem. Co. v. Warner-Jenkinson Co., 62 F.3d 1512, 1517 (Fed. Cir. 1995) (citing Graver Tank & Mfg. Co., v Linde Air Prods. Co., 339 U.S. 605, 610, 70 S.Ct. 854, 857 (1950))

5. e.g., Sanitary Refrigerator Co. v. Winters, 280 U.S. 30, 50 S.Ct. 9 (1929), Specialty Equip. & Machinery Corp. v. Zell Motor Car Co., 193 F.2d 515, 519 (4th Cir. 1952); Atlas Powder Co. v. E.I. Du Pont De Nemours & Col., 750 F.2d 1569 (Fed. Cir. 1984).

6. Lockheed Aircraft Corp. v United States, 213 Ct. Cl. 395, 553 F.2d 69 (1997), Jamesbury Corp. v. United States, 518 F.2d 1384, 207 Ct.Cl. 516 (1975); Graver Tank.