What Does Therasense Mean for Reexamination?

Scott Daniels | June 1, 2011

Last week’s en banc decision by the CAFC in Therasence v. Becton, Dickinson, establishing a “but-for” test for the materiality prong of inequitable defenses, promises to ease substantially the burden on patent applicants to flood the examiner with prior art references.  Applicants still must submit references that are material under PTO Rule 1.56, but no longer face the prospect of unenforceability if they err in doing so – a reference is material for an inequitable conduct defense in litigation only if the patent would not have issued “but-for” the non-disclosure of that reference to the PTO. 

What about reexamination?  For the most part, there will be little change.  Certainly, the possibility of establishing that a reference is material is one of the collateral benefits from requesting reexamination for an accused infringer.  Yet, establishing materiality is rarely the primary motivation for filing a request. 

Nonetheless, to determine whether an undisclosed reference would have blocked issuance of a patent, a court must place itself in the shoes of the original examiner.  The issue is patentability, not validity.  A court must give the patent claims their “broadest reasonable scope,” not their scope under Markman as in litigation.  Further, the standard of proof for patentability at the PTO is preponderance of the evidence, not clear and convincing evidence. 

Accordingly, in the right case, where the undisclosed reference is especially strong, reexamination will be the best way to determine whether that reference would have prevented the patent from issuing.  Even those trial judges who are normally reluctant to defer to the PTO reexamination results, might regard the issue of materiality as one that should be determined by reexamination. 

Also, a determination that a reference affects unpatentability (i.e., the reference is material) under PTO standards is not necessarily a determination that the patent is invalid under District Court standards.  Accordingly, there is still a strong incentive for an accused infringer to prevail with an inequitable conduct defense.

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