The duty of disclosure in the post-Therasense landscape.

*Birch, Stewart, Kolasch & Birch, LLP, Suite 100 East, 8110 Gatehouse Road, Falls Church, VA 22042, USA Tel.: +1 703 205 8000 Fax: +1 703 205 8050 E-mail: [email protected] In Greek mythology the Hydra was a multi-headed creature, with the singular a ttribute that if one head was cut off two heads would grow. Today a hydra is “a persistent or multifaceted problem that cannot be eradicated by a single effort” [101]. Section 37 C.F.R. §1.56 states, in part, that the duty of disclosure “ includes a duty to disclose to the Office all information known to that individual to be material to patentability as defined in this section” [1]. Inequitable conduct may be found, and a patent held unenforceable, when information material to patentability is intentionally withheld from the USPTO. Beginning around 10 years ago, US courts created a hydra through several decisions regarding the duty of disclosure [2–5]. With these cases, the courts developed a sliding scale test, in which materiality of the information was balanced against ‘intent’ [4] . Using the sliding scale, if the information was found to be highly material, intent could be inferred. Because of this test, applicants would submit hundreds of documents, which were of little to no relevance to the patentability of the claims under examination, in an effort to comply with the heightened duty of disclosure. Compliance with the duty of disclosure in the USA became a hydra where no matter how much information the applicant submitted to the USPTO, there seemed to always be more prior art or information that could be submitted. Concomitant with this was the effect on litigations where it has been estimated that up to 80% of patent litigations included an affirmative defense of inequitable conduct for failing to comply with the duty of disclosure [6]. Recognizing the nearly impossible compliance standard that was created, in particular by the sliding scale test, the Court of Appeals for the Federal Circuit (CAFC) revisited the duty of disclosure in the en banc decision of Therasense Inc. v. Becton Dickinson and Co. [7]. The invention in Therasense involved a single-use disposable electrode strip. The element at issue was the feature that the electrode was configured to be exposed to a blood sample ‘without an intervening membrane’ [7]. The applicant distinguished the invention from a prior art reference by arguing that, in the reference, the membrane was considered to be an essential feature. However, in Europe, the applicant characterized the membrane in the European equivalent of the US reference as preferred, but not necessary. The applicant did not submit the statements made before the EPO to the USPTO. In the en banc decision, the court first newly defined materiality as being a ‘butfor’ materiality. Under this standard, ‘but-for’ materiality is met if the USPTO “would not have allowed a claim had it been aware of the undisclosed prior art” [7].