Chinta & Fratangelo LLP

Prosecution Laches as Defense to Infringement — Cancer Res. Tech. Ltd. v. Barr Labs., Inc.

Prosecution laches is an equitable defense to a charge of patent infringement. Symbol Techs., Inc. v. Lemelson Med., 277 F.3d 1361, 1366 (Fed. Cir. 2002).  The doctrine “may render a patent unenforceable when it has issued only after an unreasonable and unexplained delay in prosecution” that constitutes an egregious misuse of the statutory patent system under the totality of the circumstances. Cancer Res. Tech. Ltd. v. Barr Labs., Inc., No. 2010-1204 (Fed. Cir. 11/9/2010), slip op. at 7–8, citing Symbol Techs., 422 F.3d at 1385–86.

Cancer Res. pertained to the patent on the drug temozolomide (brand Temodar). CR and Schering owned the ‘291 patent on the drug substance, originally filed in 1982, claiming anticancer activity.  In the prosecution history of the ‘291 patent, the original application was rejected for lacking data showing activity.  In response, the applicant abandoned the application and filed a continuation.  This cycle was repeated eight times over a nine-year period with no further argument by the applicant. The ownership changed in 1991 to CR, and CR made new arguments.  There were a few more continuations, but the patent was allowed and issued 11/9/1993. The drug Temodar was approved 8/1999.  Schering (US licensee) obtained a §156 extension.

Barr filed an ANDA and was sued.  Barr stipulated to infringement and validity, but counterclaimed that the patent was unenforceable for prosecution laches and inequitable conduct. The dist ct agreed with Barr on both claims. The district court found that the delay caused by eleven continuation applications, ten abandonments, and no substantive prosecution for nearly a decade was unreasonable and a sufficiently egregious misuse of the patent system to bar enforcement of the ’291 patent for prosecution laches.

On appeal, the Fed. Cir. reversed b/c there was no prejudice during prosecution, i.e., that the accused infringer or others invested in, worked on, or used the claimed technology during the period of delay. Slip op. at 9.  Barr argued that the public was prejudiced – this was rejected the panel.  The panel held “that to establish prejudice an accused infringer must show evidence of intervening rights,  i.e., that either the accused infringer or others invested in, worked on, or used the claimed technology during the period of delay.”  Id.  The validity of the patent was upheld on the prosecution laches issue.

The Federal Circuit panel also found no inequitable conduct. The inventor withheld information from the USPTO during prosecution, but asserted that it was without intent to deceive.  This argument was rejected by the District Court.  The Federal Circuit majority reversed, and held that the District Court improperly equated the intent from the materiality of the data. Id. at 16–17.  The majority states that materiality and intent are different requirements. Id. at 17, citing Larson Mfg. Co. v. Aluminart Prods. Ltd., 559 F.3d 1317, 1340 (Fed. Cir. 2009).

Prost dissented on both the laches and inequitable conduct holdings.  On the laches issue, she asserted that “the majority propounds a new and unsupportable legal standard for prosecution laches.” Prost did not agree that a showing of intervening rights, i.e., prejudice, is part of Federal Circuit precedent.  Prost would hold that the public has an interest in timely patent prosecution.  Prost dissent at 5.  Further, in this case where the pre-GATT law applies, the delay in prosecution effectively extended the term of the patent.  Id. Prost also suggests there is no basis for limiting the period of harm to the time that the patent prosecution was delayed.  Id. at 6.

Prost would also have upheld the District Court on the inequitable conduct issue. She asserts the majority erred by determining that materiality and intent require separate evidentiary bases. Prost agreed with the District Court credibility determinations, and asserted that the majority incorrectly dismissed the District Court findings.