C.A.G. Insights

Pre-Litigation Patent Correction Procedures

So, to give your business an “edge,” you invested in a team of innovative professional engineers and scientists.  It paid off: you developed and perfected advanced technologies, as compared to your competitors. But, now they seem to have adopted your technologies to compete with you.  However, you took the precaution to obtain patent rights.  Now might be the time to exercise those rights and protect the return on your R&D investments.

Before proceeding, there are a host of factors to consider, including broader business and market strategies, in addition to the “purely legal issues” posed by filing a patent lawsuit.  As to the legal issues, at the outset one is plainly “due diligence.”  This includes simply taking those steps that a reasonable, prudent businessman would take.  One of these steps is to have a person skilled at reading patent claims, a patent lawyer, take a look at the issued patents, and compare the patent claims with the technology (products, devices, systems or processes) that your competitors are offering. In making a preliminary assessment, a review of the patent claims and the patent file history (the communications with the US Patent Office during prosecution of the patent) is necessary.  From this review, and perhaps additional prior art searches, it might become apparent that it would be necessary, or desirable, to make some changes to the patent claims to improve your chances of success in a patent infringement law suit.

There are several procedures available to the patent owner to make corrections or amendments to an issued patent in the Patent Office.  The selection of the type of procedure depends upon the nature of the change you want to make, and in some cases, the timing of when you want to make the change.  There are essentially four procedures that a patent owner can use to make corrections to an issued patent: (1) certificate of correction; (2) reissue; (3) ex parte reexamination; and (4) supplemental examination.   (There is also a possibility of filing a “disclaimer” to disclaim some patent claims, but it is seldom used and not further discussed here.) Each of these listed four Patent Office proceedings is designed to fit certain circumstances, and patent counsel should carefully consider which is the most appropriate to use.

I Certificate of Correction:

Correction is a relatively simple procedure that can be used to correct typographical errors or those that are of a “clerical” or minor nature.  The errors may arise during the printing process of the patent, and could be the fault of the Patent Office. In that case, the correction can be obtained for no fee.  On the other hand, if the error is one that was introduced by the applicant for patent, then there is a correction fee.  A change that would broaden the scope of a claim is not regarded as “minor,” and other procedures would have to be used, if that kind of correction is desired.  A request for a certificate of correction does not reopen prosecution, and so the Examiner cannot issue Office Actions rejecting the claims over prior art, or for any other reason. The Patent Office either agrees to the changes, or denies the request stating reasons for the denial. 

II Reissue

A reissue proceeding is the most common, and it can be used to amend and correct a patent which is regarded as “wholly or partly inoperative or invalid, through error without any deceptive intention,” by reason of either a defective specification, or drawing, or by reason of the patentee claiming more or less than he/she had a right to claim in the patent.  35 USC § 251.  A reissue proceeding can be used to broaden the scope of the patent claims if the claims were drafted too narrowly, as long as the reissue application is filed within two years of the issue date of the patent. Thus, if the competitor’s product is outside the scope of the claims, then it may be possible to broaden the scope with a reissue application.  If two years have already elapsed, then a reissue cannot broaden the patent claims, but it can be used to correct errors, or narrow the scope of the claims. It is therefore a useful exercise to look at your patent claims just before the passage of two years, to see whether filing for reissue might be necessary, or useful. While narrowing of the claim scope can sometimes be necessary, for example, to avoid newly-discovered prior art, a broadening reissue is likely to be more useful, if not time-barred, when a competitor has attempted to design around your patent.

Importantly, the reissue proceeding re-subjects the patent to an examination, and one can expect that Office Actions may be issued challenging the patentability of the amended patent claims.  Sometimes prior art that was previously cited, and over which the patent was originally granted, might be raised again.

A cautionary factor is that a competitor might have acquired “intervening rights” if the scope of the claims that are allowed to issue from the reissue proceeding is “substantively” different from the scope of the original claims. These intervening rights may cut off the capability to seek damages for past infringement.  35 USC § 252.  However, if the claim language was not substantively changed, and the corrections made related to text in the specification or drawings, for example, then such intervening rights do not arise.  A further caution is that courts have found “equitable intervening rights” in instances where an infringing party made significant investments based on advice that the patent claims were invalid, or not infringed, based on the “errors” in the patent. These equitable intervening rights may cut off future claims for damages, even if the party infringes the reissued patent claims. 

Intervening rights are also a factor to bear in mind when filing for ex parte reexamination, supplemental examination, or post grant review.  Accordingly, as a preliminary matter, careful consideration should be given to the scope of the claims.  Ask: “What scope is necessary to both overcome the “errors” that prompted filing for correction, and also overcome any anticipated prior art that could be cited in the re-prosecution?”  The scope should “thread the needle,” if possible, by avoiding a substantive change that triggers intervening rights, while still ensnaring the accused technology in the claims.  It goes without saying that this requires the skills of experienced patent counsel that appreciates both claim construction in a litigation context, as well as claim interpretation in the US Patent Office.

III.  Ex Parte Reexamination

Ex Parte Reexamination is the only type of reexamination now available after the America Invents Act (“AIA”). In general, anyone can apply for reexamination of an issued patent, at any time during its term.  The requirement for an ex parte reexamination to go forward is that there is a showing of a “substantial new question of patentability.” Such a new question is usually premised on newly-discovered prior art that was not available to the US Patent Office Examiner at the time of the prosecution of the original patent. But, previously considered “old” prior art that the Examiner was aware of can also be submitted as a basis for the question, if it is presented in a new light. The prior art should either anticipate the patent claims, or render them “obvious.” Once filed, the Patent Office must issue a decision within three months on whether to proceed on grounds of the asserted new question of patentability.  (In the first 2 years post grant, claim scope can be enlarged in a reissue proceeding, of course.)

If the reexamination application was filed by the patent owner, then it should be accompanied not only by the prior art, and a detailed explanation of the new question of patentability as to each claim at issue, but also an amended version of these claims that are patentable over the prior art. The patentee can amend the patent claims as long as the scope of the claims is not enlarged. 

Not only does the patent owner has the right to seek reexamination; others can do so as well. So a competitor might use this avenue to try to invalidate patent claims as a defensive tactic to eliminate a risk of a patent infringement lawsuit.  In such an instance, the patent owner must await the Patent Office’s Decision granting the requester’s reexamination application, and can only then file an Owner’s Statement.  This statement can present arguments as to why the claims are valid over the prior art and can also present claim amendments.

As explained above, intervening rights may apply to claims amended during the ex parte reexamination proceeding.  Accordingly, the same precautions apply.

IV  Supplemental Examination

This type of examination was enabled by the AIA, and is therefore relatively new.  Only a patent owner may request supplemental examination of a patent to “consider, reconsider, or correct information believed to be relevant to the patent.”  This standard is much broader than a mere consideration of prior art publications, as in an ex parte reexamination, and includes consideration of whether the claims cover patentable subject matter under 35 USC § 101, or are inoperative or defective under 35 USC § 112 (relating to claim and specification interrelation, and formality issues).  Most significantly, it is the only procedure that can be used to cure potential patent unenforceability based on conduct that might be regarded as “inequitable.” Accordingly, it can be a useful mechanism to remove the potential issue of unenforceability from the infringer’s defenses in litigation.

The Director must conduct the supplemental examination and issue a certificate within 3 months indicating whether there is a new question of patentability, or not.  If there is at least one, the Director will order ex parte reexamination (see, part III above).  This reexamination is conducted under the Patent Office rules for ex parte reexamination, except of course, that issues may include others beyond lack of novelty or obviousness of the claims. The owner has no further right to file a Statement.  But, as the only party able to seek supplemental examination, the owner has the capability to file a wide range of information at the outset along with the request. Again, retaining experienced patent counsel is necessary to ensure that the initial filing is comprehensive and designed to meet litigation goals. 


From the foregoing, it is apparent that if the preliminary due diligence finds issues with the original patent that may make its enforcement more difficult in a court, these issues may be corrected in a variety of ways through proceedings in the Patent Office. The simplest, lowest cost, but most limited in scope, is the use of the certificate of correction process.  The reissue and ex parte reexamination proceedings are more robust and broader in scope of correction available. And, the AIA supplemental examination offers the unique possibility to remove potential patent unenforceability.  Each of these proceedings has its uses, and competent patent counsel should be retained to advise which is the most suitable under the circumstances.