New data shows a marked decrease in the number of new reissue applications, which have fallen by about half since peaking five years ago. This drop is theorized by some to be a retrenchment on the widely used technique of filing for reissue to insulate patents from challenge in third-party reexaminations. That hypothesis is reasonable, given that ex parte reexamination filings are also down by about half over the same period.

Reissue offers patent owners the advantage of presenting prior art in a forum they control, blocking the same art from being presented in the more hostile environment of a reexamination set up by a third-party challenger. An ex parte reexam cannot reconsider issues addressed by an examiner in an earlier proceeding, such as a reissue.

Despite the drop in reexams, third-party challenges to patents have not disappeared. Rather, IPRs have eclipsed ex parte reexams, with the rate of IPR filings exceeding the rate of ex parte reexams even at its peak. Patent owners, it would seem, still have the same or even greater incentive to insulate patents from challenge in an IPR.

A significant difference, however, is that reissue does not have the same effect on an IPR as it does on a subsequent ex parte reexam. The Patent Office is precluded from initiating an ex parte reexam unless a request presents a substantial new question of patentability. In an IPR, the PTAB may, but need not, forego institution if the same art was previously considered by the Patent Office. While denying institution is possible, it seems more the exception than the rule.

Nonetheless, reissue applications should not be overlooked entirely. As we have previously noted, the success rate for amending claims in an IPR is very low. If claim amendments are necessary or desirable, filing a reissue may be a much better path than attempting to amend in an IPR.

As always, when faced with an IPR challenging a valuable patent, it is important to consider all possible avenues to win, including reissue.