Federal Circuit rules that prosecution laches requires evidence of prejudice
By Jonathan Allred – Edited by Elizabeth Akerman
Cancer Research Technology Ltd. v. Barr Laboratories, Inc., No. 2010-1204 (Fed. Cir. Nov. 9, 2010)
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. (more…)