The Zoltek versus the United States case might be characterized as if at first you don’t succeed, try, try again…and then try one more time. Zoltek took three trips to the Federal Circuit before having the validity of its patent for materials used in the B-2 bomber and F-22 fighter planes confirmed. Even before filing its suit, Zoltek had tried again at the Patent Office through a reissue patent application. With the increasing challenges of proving infringement and maintaining the validity of patents, reissue applications provide a useful tool for adjusting claim scope after the patent issues.

The purpose of a reissue application is to “correct an error in the patent, where as a result of the error, the patent is deemed wholly or partly inoperative or invalid.” MPEP 1402. With respect to claim scope, the most common errors are that the claims are too narrow or too broad. Id. The office, however, limits the time period for filing a broadening reissue to two years from the issue date of the patent. Provided that there was no unreasonable delay, a narrowing reissue application may be filed at any time during the patent’s life. (For a related article, see Addressing Section 101 Issues Through Reissue.)

Zoltek filed its reissue application just before the two-year anniversary of the underlying patent’s issue date. As illustrated in the excerpt below, Zoltek broadened its claim by removing the step of oxidizing and stabilizing the carbonizable fiber starting material at a specific elevated temperature and made other adjustments to clarify its claim:

A method of manufacturing a plurality of different value controlled resistivity carbon fiber sheet products employing a carbonizable fiber starting material; said method comprising [oxidizing and stabilizing the carbonizable fiber starting material at an elevated temperature of the order of 220 degrees Centigrade to effect molecular aromatic rearrangement of the fibers,] selectively partially carbonizing [the] previously oxidized and stabilized fiber starting material for a predetermined time period in an oxygen free atmosphere within a furnace at [a] selected temperature values within a temperature range from 370 degrees Centigrade to about 1300 degrees Centigrade …[1]

This change to the claims removed the step of creating a starter material for the carbon fiber sheets. Although the Court of Federal Claims (CFC) bifurcated invalidity and infringement, the importance of this step’s removal to infringement is evident from the government’s argument that the specification does not support all of the steps of the claim being performed by different entities. Factually, the government’s contractor, Lockheed, had outsourced the manufacture of the starting material to a Japanese entity for at least some of the accused carbon fiber panels.

The CFC agreed with the government and considered Zoltek’s claims invalid for failing to meet the written description requirement under 35 U.S.C. 112. The CFC reasoned that the amendment to remove the oxidizing step impermissibly broadened the patent because its elimination exceeded the written description in the original patent. The Federal Circuit reversed, reasoning that the removal of this step was a proper broadening of the claim since the reissue was within its two-year window. In terms of support in the written description, the Federal Circuit further reasoned that the addition of the word previously had been required by the examiner during the reissue process as an acknowledgment that the specification indicated that the starter material is commercially available and could be made or purchased before performing the remaining steps in the claim. Consequently, the written description supported a claim that removed the oxidizing step used to create the starter material. The Federal Circuit’s finding that the reissue claim removing this step is valid paves the way for Zoltek’s argument that the government, through its contractor, directly infringed the reissue patent.

Zoltek thus demonstrates that a broadening reissue may be used to improve infringement positions. For example, when multiple parties are involved in performing a process or making an accused product, removing an element or step may change the argument from indirect infringement (inducing infringement or contributory infringement) to direct infringement. This may become increasingly important in the wake of the Supreme Court’s Commil v. Cisco opinion, which reemphasized that indirect infringement requires proof that an indirect infringer intended to infringe the patent.

A narrowing reissue can also be used to improve an infringement position by heading off invalidity arguments. For instance, later discovered prior art, patent written description requirements, or subject matter eligibility requirements may require rewording or narrowing of the claims to ensure validity.

Another advantage of the reissue application process is the ability to file continuation applications based on the reissue application. This provides flexibility to continue to amend claims even after a reissue patent has been granted. This allows the patent owner to use the granted reissue patent against potential infringers, while providing the flexibility to adjust the claims in a reissue continuation application if unforeseen noninfringement or invalidity arguments arise during enforcement of the first reissued patent.

Given the ability of the reissue patent to correct errors in a patent or place it in better condition for enforcement, it is prudent to consider whether a reissue application would be beneficial before the close of the two-year broadening reissue window and before any enforcement action.

Data based on USPTO  2015 Annual Report 2011 2012 2013 2014 2015
Applications Filed – reissue 1158 1212 1074 1207 887
Patents Issued – reissue 969 921 809 661 531
Percentage Issued 83.68% 75.99% 75.33% 54.76% 59.86%

While a reissue application can provide significant advantages, the decision to file a reissue application requires careful consideration. In doing so, there is a risk that all patent rights would be lost or narrowed to the point that they are ineffective. Statistics from the patent office, above, indicate that examination of reissue patents has become more rigorous in that, as a percentage, fewer reissue applications are being allowed.

Also, there are significant limitations on the filing of a reissue application. In particular, the reissue must relate to the same invention as the original patent, and a reissue will not be granted to recapture subject matter surrendered to obtain the original patent.

Overall, the Zoltek case illustrates the complexity of enforcing patents and reminds us that a reissue patent is one useful tool available to correct errors in a patent after its issue date.

[1] RE 34,162 a reissue of 4,728,395 [emphasis added]