Post-Interference Ex Parte Prosecution by a Losing Applicant InterferentJun 2003 – Intellectual Property Today, Vol. 10, No. 6 at page 26,
Regrettably, the PTO does not permit winning interferents to participate in losing applicant interferents’ post-interference prosecution. In re Temple, 231 USPQ 492 (Comm’r 1986). Even more regrettably, many examiners do not understand 37 CFR 1.658(c) (which codifies the law on interference estoppel)—or, at least, do not apply it as vigorously as I think appropriate. The result is that well-represented losing applicant interferents can occasionally eke out amazing claims in post-interference ex parte prosecution—sometimes destroying much of the value of the winning interferent’s hard fought (and expensive) victory.