Cancer Research Technology Ltd. v. Barr Laboratories, Inc.: Federal Circuit rules that prosecution laches requires evidence of prejudice

Cancer Research Technology Ltd. v. Barr Laboratories, Inc., No. 2010-1204 (Fed. Cir. Nov. 9, 2010)

Slip Opinion

The Federal Circuit overturned the District Court of Delaware, which had ruled that the plaintiff’s patent was unenforceable for prosecution laches, and, in the alternative, invalid for inequitable conduct.

Prosecution laches is an equitable defense to infringement when the plaintiff has delayed the prosecution of a patent application unreasonably. In this case, the Federal Circuit held that prosecution laches requires a finding of prejudice – evidence that the accused infringer “invested in, worked on, or used the claimed technology during the period of delay” – in addition to an unreasonable delay in prosecution.

As the opinion notes, the usefulness of the doctrine will be limited now that patent terms are measured from the effective filing date and not the date of refilling.

The Federal Circuit also overturned the Delaware court’s ruling on inequitable conduct.

Patently-O offers a synopsis and disagrees with the dissent. Inventive Step summarizes the opinion. The Patent Prospector provides the text of the opinion with commentary sympathetic with the dissent interjected throughout.

The original patent application for temozolomide, the subject matter of the ‘291 patent at issue in the case, was filed in 1982 by a British pharmaceutical company. The examiner rejected this first application for an insufficient showing of utility based on animal tests alone. Between then and 1991, rather than respond to the rejection, the applicant filed nine continuations. In 1991, Cancer Research obtained rights to the patent application and filed yet another continuation, which was rejected as the others. However, Cancer Research responded to the rejection, arguing that animal data was sufficient to establish utility. The claims were allowed and the ‘291 patent granted on November 9, 1993, set to expire in 2014.

The majority interpreted both Supreme Court and this court’s precedent to require a showing of prejudice through intervening rights. Since defendant Barr did not develop a generic version of the drug until 2007 and had no other evidence of prejudice, the standard for prosecution laches was unmet.

In her dissent, Judge Prost objected to the majority’s standard for prosecution laches. First, she disagreed that precedent requires showing prejudice in addition to unexplained and unreasonable delay. Rather, she argued that the court should have applied the “totality of circumstances” standard presented in Symbols Technologies, Inc. v. Lemelson Medical, 422 F.3d 1378 (Fed. Cir. 2005). She also objected to language in the majority opinion that limits the analysis of prejudice to the period of delay, which she called an unexplained and unsupported temporal limitation to the standard. She argued that such a limitation ignores the harm to the public that occurs many years following the original disclosure, when the patent would have expired if prosecuted in a timely fashion, but does not because of the delay in prosecution. The majority responded that the public benefited because Cancer Research was induced to develop and market temozolomide by the patent protection it received, and that Cancer Research ran the risk that another company would develop the technology during the delay and claim prosecution laches.

Jonathan Allred is a 2L at the Harvard Law School.