In re Tanaka

By Michael B. Marion

At the end of 2009, the USPTO Board of Patent Appeals and Interferences handed down a decision that surprised many patent practitioners–a patentee could no longer add narrower claims through reissue without amending or canceling the broader independent claim.1 Last year, the Federal Circuit ruled on In re Tanaka and reversed the USPTO, explicitly blessing the long-standing practice of adding narrower claims through reissue.2 Despite the Federal Circuit’s approval, there are still pitfalls and unresolved questions that patent practitioners should know before filing a reissue for adding narrower claims.

This article will begin by providing a brief review of the Tanaka decision. Next, an important caveat concerning the reissue application itself is explored. Lastly, the dual requirement of “error” within the reissue statute will be discussed in view of the Tanaka decision and a key prior decision of the Federal Circuit.

I. The Federal Circuit in Tanaka Approved Using the Reissue Statute To Add Claims of Narrower Scope As a Mere Hedge Against Invalidity

The Tanaka case presented a question of pure law concerning one of the basic requirements of a reissue application—the requirement of an “error.” As originally filed, the patentee in Tanaka sought to broaden the patent’s sole independent claim.3  However, through a series of amendments, the reissue applicant abandoned any attempt to broaden the independent claim, and rather only sought the addition of a narrower dependent claim. The reissue applicant submitted a substitute declaration stating that “‘because I did not fully appreciate the process of claiming according to U.S. practice, I did not realize that I had claimed more or less than I was entitled to claim.’”4

The Examiner rejected the claims of the reissue application for filing to specify an error that could be corrected through reissue, as the broadest claim remained the same.5 The BPAI affirmed the Examiner’s rejection, finding “Tanaka was impermissibly seeking an additional claim on reissue ‘in order to hedge against the possible invalidity of one or more of the original claims.’”6

On appeal, the Federal Circuit reversed the USPTO by a majority 2-1 panel, explicitly holding that “adding a dependent claim as a hedge against possible invalidity is a proper reason to seek reissue.”7 In support of its decision, the majority expounded on a multiplicity of reasons additional dependent claims may be beneficial, including how claims of narrower scope can be useful to clarify the meaning of broader, independent claims under the doctrine of claim differentiation and that dependent claims are also less vulnerable to validity attacks given their more narrow scope.8 Thus, the Federal Circuit concluded that the requirement of error is met as the omission of a narrower claim from a patent can render a patent partly inoperative by failing to fully protect the disclosed invention.9

II. A Tanaka-type Reissue Does Put The Patent At Risk

As the Federal Circuit noted, the holding of Tanaka is a “narrow rule,” but this decision was consistent with prior decisions, rather than a significant departure from established patent practice. Probably more important than what was actually decided in Tanaka is what was not decided. Adding narrower claims through reissue is indeed permissible, it is not a “free pass” to indiscriminately add claims to a patent.

To begin with, it is significant that, fundamentally, the patentee seeking to add only narrower claims is still putting his patent through reissue. Despite Judge Dyk’s characterization in dissent in Tanaka that a patentee who is only adding narrower claims is not risking anything,10 a patent in reissue is nonetheless at risk. A patent in reissue enjoys no presumption of validity.11 Accordingly, a zealous examiner could pursue a further search for prior art to invalidate the original claims in the patent during reissue. Even if ultimately, the reissue applicant abandons the reissue application (and thereby reverting to the originally-issued patent), the patent could be seriously weakened by the newly-created prosecution history in the reissue application.12

III. A Reissue Application Seeking To Add Only Narrower Claims Must Still Demonstrate An “Error In Conduct”

It is also important to remember that Tanaka only addressed half of the “error” issue in the reissue statute. ”[The] statutorily required ‘error’ of section 251 has two parts: (1) error in the patent, and (2) error in conduct.”13  Tanaka was only concerned about the error in the patent. However, the reissue applicant must ultimately establish the existence of both requisite errors in the reissue statute.

When filing a reissue application, the applicant must submit a reissue declaration, averring that that the applicant believes the original patent to be wholly or partly inoperative or invalid and identify at least one error, having arisen without deceptive intent,14  being relied upon as the basis for reissue,  The USPTO explicitly does not require applicant to explain how or when the error arose, occurred, or was discovered.15 Nevertheless, the existence of the error in conduct is critical in any attempt to enforce the reissue patent.

In Hewlett-Packard v. Bausch & Lomb, the Federal Circuit held that newly-added narrower claims from a reissued patent invalid for failing to comply with the “error in conduct” requirement of Section 251.16 In that case, the patent agent who prosecuted the original application had submitted two affidavits in support of the reissue application seeking to add claims of narrower scope.17 The patent agent attested to “limited” contacts with the inventors during the preparation of the original patent application as the basis for having omitted the narrower claims.18 However, documentation uncovered during subsequent litigation showed that the inventors and the agent had many conversations during the prosecution of the original application. The Federal Circuit characterized the affidavits as “pure fiction” and consequently found the reissue application invalid for failing to comply with the error requirement of the reissue statute.19

Although under the current rules, the USPTO will not make inquiry into the origin of the error in the patent, other than to test for sufficiency of the reissue declaration, one should assume that the basis for the error will be an issue of contention should the patentee attempt to enforce the reissued patent. A patentee who seeks to add narrower claims through reissue must be sure that there was indeed an “error in conduct” prior to filing the reissue application and corresponding declaration attesting to such error. There are any number of reasons why it was error to exclude the narrower claims, including such examples as newly-discovered prior art or a new understanding of the patent claims in view of commercial embodiments of the claimed invention. However, a patentee wanders into dangerous territory if the basis for the new narrower claims rests upon prior art known during the pendency of the original application. Although it should be possible for a patentee to demonstrate a “new understanding” of the old prior art reference based on post-issuance events, such conduct may not withstand the crucible of litigation.  

IV. Conclusion

It important to keep in mind all of the requirements of the reissue statute, and that reissue applications are not an opportunity for a “second bite of the apple” to fix all problems with the patent.  There remains on open question as to whether any reissue application would be considered a “broadening” reissue under § 251. Under the reissue statute, a reissue application “enlarging the scope of the claims of the original patent” must be filed within two years of issuance of the original patent.20 A prudent patentee should seek to add what is regarded as narrower claims within two years of issuance of the original patent so as to avoid any possible issue as to whether any added claims could be argued to be broadening.

In summary, a patentee should be able to add claims of narrower scope through reissue without having to amend the broader claims of the originally-issued patent. Tanaka was a sound decision favoring the rights of the patent holder—a patent has little value if it cannot be enforced. Ultimately, the Federal Circuit’s decision permits patent holders to reinforce their patents through the reissue process to ensure full protection of their patent rights. 


  1. Ex Parte Tanaka, App. No. 2009-234 (BPAI Dec. 9, 2009).
  2. In re Tanaka, 640 F.3d 1246, 1250 (Fed. Cir. 2011).
  3. Id. at 1247.
  4. In re Tanaka, 640 F.3d at 1247-48.
  5. Id. at 1248.
  6. Id.
  7. Id. at 1250.
  8. Id. at 1250-51.
  9. Id. at 1251.
  10. Id. at 1255 (Dyk, J., dissenting).
  11. 37 C.F.R. § 1.176.
  12. See 37 C.F.R. § 1.111(a) (reissue files are open to the public).
  13. Hewlett-Packard Co. v. Bausch & Lomb, Inc., 882 F.2d 1556, 1564 (Fed. Cir. 1989).
  14. 37 C.F.R. § 1.175. It is noted that the America Invents Act § 20 removes the requirement pertaining to deceptive intent, However this does not change the analysis of the requisite error.
  15. M.P.E.P. § 1414.
  16. Hewlett-Packard, 882 F.2d at 1566.
  17. Under an earlier version of Rule 1.175, the reissue applicant was required demonstrate how the error in the patent arose as part of the reissue application. The current rule no longer requires this showing by the reissue applicant.
  18. Id. at 1561.
  19. Id. at 1562, 1566.
  20. The patentee in Tanaka filed the reissue application within two years, and thereby avoided the issue of broadening reissue.