The priority date of a patent is an important aspect in protecting intellectual property. The priority date is the earliest possible filing date that a patent application is entitled to rely on; it is based on the filing dates of any related patent applications that were filed before the application (the priority chain).  This date determines which prior art can be used by the Patent and Trademark Office to determine patentability of the invention and which prior art can be used by competitors to challenge the patent’s validity.

The priority date must be asserted when the patent application is filed.  It is difficult, and sometimes not possible, to correct the priority date if it is not asserted, or improperly asserted, when the application is filed.  Thus, patent attorneys must be careful to make sure that the correct priority date is stated in the application at the time of filing.

This issue was recently addressed by the Federal Circuit Court of Appeals in Honeywell International v. Arkema Inc., 2019 U.S. App. LEXIS 29478 (October 1, 2019).  In that case, Honeywell filed a patent application in 2014 with a priority date of 2002.  The patent application was amended during prosecution to change what was claimed as the invention, but the applicant failed to change the priority chain to list the related applications that corresponded to the invention as claimed.

The patent was issued in 2015.  Shortly thereafter, Arkema filed two petitions for post grant review, challenging the patent in the Patent Trial and Appeal Board.  Arkema alleged that the patent application was not entitled to the 2002 priority date because the claims, as amended, were not supported by the related applications going back to 2002, but were only supported by the 2014 application itself.  According to Arkema, the priority date was 2014, not 2002.  Based on the 2014 date, Arkema alleged that the patent was invalid due to prior art that became known between 2002 and 2014.

Honeywell argued that it had failed to list the correct related applications in the priority chain.  Honeywell requested that the PTAB permit it to file a motion for leave to file a petition to the Director of the PTO for a Certificate of Correction to correct the priority chain.

Under 35 U.S.C. § 255, a patent owner must seek to correct a patent by filing a petition to the Director of the PTO for a Certificate of Correction.  In order to obtain a Certificate of Correction, the patent owner must satisfy three requirements: (1) the error must not be the fault of the PTO and must be a clerical or typographical error or another minor error; (2) the error must have been made in good faith; and (3) the correction must not constitute new matter in the patent application.

If a patent is under post grant review in the PTAB, the patent owner cannot file a petition for a Certificate of Correction until it first obtains authorization from the PTAB.  To do that, the patent owner must request leave from the PTAB to file a motion.  If leave is granted, the patent owner must then file a motion in the PTAB requesting that the PTAB cede its jurisdiction back to the PTO Director; if the motion is granted, then the patent owner may file its petition for a Certificate of Correction to the Director.

Honeywell followed the proper steps.  However, the PTAB denied Honeywell’s request and found that the requirements of § 255 were not met.  The post grant review process was then completed, and the PTAB invalidated the claims of the patent.  Honeywell appealed.

The Federal Circuit reversed the PTAB, holding that the PTAB abused its discretion by ruling on whether the requirements of § 255 were met.  The court explained that the authority to decide whether a Certificate of Correction is appropriate belongs only to the PTO Director, not to the PTAB, and that the PTAB cannot decide the merits of the issue.  The PTAB only has the authority to decide the patent owner’s request for leave to file a motion in the PTAB and to decide that motion.

The court found that the PTAB had improperly denied Honeywell the opportunity to file a motion, basing its decision on its view of whether a petition to the Director would be successful.  The PTAB should not have reached the merits at all, let alone without the patent owner being permitted to file a motion.  The court noted that a Certificate of Correction is an appropriate way to correct a priority chain in a patent.  The court vacated the PTAB’s decision and remanded the case to the PTAB, directing the PTAB to allow Honeywell to file its motion asking the PTAB for permission to file a petition to the Director to correct the patent’s priority chain.