When a patent issues with a mistake, a certificate of correction can be obtained to correct it under certain circumstances.  35 U.S.C. §§ 254, 255.  When an issued claim "omits a material limitation, and such omission is not evident on the face of the patent, the patentee cannot assert that claim until it has been corrected by the PTO. " H-W Tech., L.C. v. Overstock.com, Inc., 758 F.3d 1329, 1335 (Fed. Cir. 2014).

H-W Technology was an appeal from an infringement suit asserting U.S. Patent No. 7,525,955 ("the '955 patent"), in which H-W Technology ("H-W") alleged infringement of claim 9, among others.  Claim 9 recites a "method for performing contextual searches on an Internet Phone (IP) phone."  Id. at 1333.  In relevant part, the method of claim 9 as allowed by the U.S. Patent and Trademark Office (USPTO) recites steps of receiving search criteria from a user, submitting those criteria to a server, and receiving a list of merchants matching the search criteria from the server, "wherein said user completes a transaction with at least one of said merchants listed without the need to generate a voice call."  Id.  Issued claim 9, however, mistakenly omitted the limitation italicized above.  Id.  H-W asserted uncorrected claim 9.

H-W obtained a certificate of correction for claim 9 after filing its complaint, but did not amend its complaint to refer to corrected claim 9.  H-W did request that the district court order correction of claim 9.  The district court refused, did not consider the certificate or correction, and instead held claim 9 indefinite on summary judgment. 

The Federal Circuit first considered H-W's argument that the district court should have corrected claim 9 on its own authority.  Such an action can be taken when "the error is evident from the face of the patent."  Grp. One Ltd. v. Hallmark Cards, Inc., 407 F.3d 1297, 1303 (Fed. Cir. 2005).  The court found that nothing in the '955 patent itself made the error evident.  Among other things, claim 9 "reads coherently without the missing limitation," and the limitation appeared in the specification as an optional feature.  H-W Tech., 758 F.3d at 1333-34.  The court acknowledged that the USPTO's error was "clear on the face of the prosecution history," but noted that "evidence of error in the prosecution history alone [is] insufficient to allow the district court to correct the error."  Id. at 1334.

Turning to whether the certificate of correction should have been considered, the Federal Circuit noted that a "certificate of correction is only effective for causes of action arising after it was issued."  Sw. Software, Inc. v. Harlequin Inc., 226 F.3d 1280, 1294-95 (Fed. Cir. 2000).  There was no argument that this suit involved causes of action that arose after the certificate was issued.  Thus, the district court correctly did not consider the certificate.

The Federal Circuit then addressed whether H-W should be permitted to assert uncorrected claim 9.  The court said no.  "To hold otherwise would potentially permit patentees to assert claims that they never asked for nor rightly attained.  Such a result would be inequitable and undermine the notice function of patents."  H-W Tech., 758 F.3d at 1335.  The court did observe that this situation is "in some ways, more akin to unenforceability than invalidity," and that "unenforceability of a patent may be cured under certain circumstances."  Id.  (Presumably, there would have been no issue of unenforceability had H-W obtained the certificate of correction at a sufficiently early stage, such as before its cause of action arose.)

As a consequence of this holding, "claim 9, as corrected, has not yet been litigated and, thus, has not been held invalid."  Id.  The Federal Circuit therefore did not reach the merits of indefiniteness for claim 9 and "str[uck] the portion of the final judgment holding claim 9 invalid," but otherwise affirmed the judgment in favor of defendant Overstock.  Id. at 1336.

This case highlights the importance of carefully reviewing issued patents, particularly the claims, for errors.  The USPTO's mistaken omission of a limitation from claim 9 as issued and the lack of timely correction resulted in the squandering of all the resources devoted to its attempted enforcement.  The unenforceability-like rule announced here effectively meant that claim 9 was illusory until corrected.  This case also shows that the issuance of a claim apparently broader than what the USPTO intended to grant is not likely to be a windfall for a patentee.

Patentees generally do not have perfect knowledge of their competitors' plans and activities, and may not know of a cause of action for infringement immediately when it arises.  If a claim is issued in mistaken form, obtaining a certificate of correction early in the life of the patent maximizes the chance that the corrected claim can be asserted against later-discovered acts of infringement.  It is therefore prudent to proofread patents when they issue, including checking each claim for printing errors against the allowed claims.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.