Noted With Interest: Recent Developments Regarding The Patent Prosecution Laches Doctrine

Prosecution laches is an equitable defense in patent litigation that dates back to the early 1900s. See Woodbridge v. United States, 263 U.S. 50 (1923); Webster Elec. Co. v. Splitdorf Elec. Co., 264 U.S. 463 (1924). An alleged infringer may invoke this defense to render a patent unenforceable if the patentee's delay in prosecution is unreasonable and inexcusable, and there is some corresponding prejudice attributable to the delay. Unlike traditional laches that is aimed at protecting a particular competitor, a primary purpose of prosecution laches is to serve the public's interest. For example, the Supreme Court has expressed that "[a]ny practice by the inventor and applicant for a patent through which he deliberately and without excuse postpones beyond the date of the actual invention, the beginning of the term of his monopoly, and thus puts off the free public enjoyment of the useful invention, is an evasion of the statute and defeats its benevolent aim." Woodbridge,