An Austin Patent Attorney’s Review of IN RE YAMAZAKI


This case discusses issues with terminal disclaimers. Specifically, this case discusses whether a terminal disclaimer can be withdrawn during reissue proceedings under 35 USC § 251 that were in effect upon issuance of a patent. The full opinion may be found here:

For procedural history, Yamazaki filed a terminal disclaimer during the prosecution on November 27, 1996 of US Patent 6,180,991 based on Yamazaki’s earlier issued patent US Patent 4,581,476, disclaiming the statutory term of the patent beyond the expiration date of the ‘476 patent (December 22, 2003).

Yamazaki made amendments to the independent claims, such as that the terminal disclaimer was unnecessary, and while the patent was still pending petitioned to withdraw the terminal disclaimer. However, the USPTO didn’t act on the petition, a notice of allowance for the ‘991 patent was issued, and Yamazaki paid the corresponding issue fee on the patent to close prosecution. As such, the terminal disclaimer remained in force.

3 months after the issuance of the ‘991 patent and more than two years after the petition to withdraw the terminal disclaimer, the PTO issued a decision dismissing the petition because a recorded terminal disclaimer may not be nullified after the corresponding patent had been granted. In response to the USPTO dismissal, Yamasaki filed a reissue patent to application to correct errors committed during prosecution, the errors being the terminal disclaimer. The PTO rejected Yamasaki’s oath and declaration and oath stating the terminal disclaimer is not an error which a reissue application could fix. Yamasaki filed an appeal, where the board held that the USPTO could not remove the terminal disclaimer under 35 USC § 251 because the statue 1) prohibits reissuing an expired patent, and 2) precludes expanding a reissued patent’s term beyond that set when the original patent reissued. Yamazaki appealed the board’s decision.

At appeal, Yamazaki argued that any disclaimed portion of a base statutory term for a patent remains available and subject to reissue as part of “the term of the original patent” specified in 35 USC § 251. The court of appeals first looked at two aspects 35 USC § 253 for their analysis of the case. The first is that the statute states that a terminal disclaimer is treated as part of the original patent, and provisions describing disclaimers of patent claims “shall thereafter be considered as part of the original patent.” Second, the court held that if a patentee’s post hoc disclaimer of an issued patent claim applies as part of the original patent such that the disclaimed subject matter is treated as if it never existed. Therefore, a terminal disclaimer filed before the issue data should be afforded the same effect.

The court of appeals reasoned that when a patent issues subject to a terminal disclaimer, the patentee therefore has not just agreed to forgo some amount of its enforceable term, but has in fact reduced the term itself by effectively eliminating the disclaimed portion from the original patent. As such, the court of appeals held that the PTO lacked jurisdiction to nullify the terminal disclaimer through reissue proceedings after issuance of the ‘991 patent.


1. Before having a patent issuance, it is very important to review the notice of allowance to resolve issues before paying the issue fee. Although in this case this issue was tied to a terminal disclaimer for a patent term, other issues may arise regarding antecedent basis in claims, drawings that need to be corrected, typos in the specification, filing an IDS, etc. Before close of prosecution, there are additional remedies that a patent attorney has that will save them a lot of trouble later down the line, if they don’t just merely pay the issue fee and allow a patent to grant.

2.  Be carefully when signing terminal disclaimers in general. It may be best practice to hold a double patenting rejection in abeyance until the close of prosecution to see if a terminal disclaimer is actually necessary. In this case, Yamazaki could have avoided the problems brought up in this case by never filing the terminal disclaimer in the first place. That being said, if your patent application claims priority to a parent case, the term of the patent is already bound and there is less harm by filing a terminal disclaimer.

3. This case brings up a good reason why it is desired to keep an active patent in a patent family. If there was an active patent in this family, Yamazaki may have been able to amend the claims in a divisional to cover a majority of the claimed subject matter in the ‘991 patent without the terminal disclaimer. Just in general having prosecution not be closed in all cases for a patent family may allow your client many benefits in the future.

By | 2012-12-11T16:54:42+00:00 December 11th, 2012|Patent Attorney Takeaways|Comments Off on An Austin Patent Attorney’s Review of IN RE YAMAZAKI