Your patent expired earlier this year. Then, just last week, you found a product that looked eerily similar to the device covered by your patent, and a little checking on the
Wayback Machine indicates that this product has been sold for several years. Fortunately, even though your patent is expired, it’s still enforceable against sales that were made
while the patent was valid. In fact, you may be able to collect damages for the six years preceding the date you file a lawsuit against a potential infringer.
But patent litigation, like any type of litigation, involves a lot of strategy. The infringer is likely to throw up roadblocks and hope you lose or just lose your appetite for the litigation. A common roadblock is to initiate a parallel proceeding, most commonly an ex parte reexamination, at the PTO. In an ex parte reexamination, typically a third party initiates the proceedings, but is no longer involved after the reexamination is declared. The PTO then reevaluates your patent in view of the prior art. If the PTO finds that all of the claims of your patent are unpatentable during the reexamination, the litigation is effectively over and the infringer hasn’t had to do much to achieve this result.
However, in a matter I recently brought before the Board of Patent Appeals and Interferences (BPAI) (adjudicative body of the PTO), the BPAI asserted that the United States Patent and Trademark Office (PTO) should interpret the claims of the expired patent in essentially the same way a court would during litigation. The clear upshot of the BPAI’s decision is that owners of expired patents who are suing or considering suing past infringers may have greater leverage during settlement negotiations and need not be as wary of reexamination proceedings.
Why would the PTO follow the court’s lead? Let’s take a step back:
As you may know, there are two primary claim construction rubrics—one used by the courts and the other used by the United States Patent and Trademark Office (PTO). Generally, the courts interpret claim terms as one who is skilled in the art would after reading the claims, specification, and file history. In contrast, the PTO uses the “broadest reasonable construction consistent with the specification” in order to interpret the claim in your patent application or patent during reexamination. Scholars of patent law find failings with the former and are wary of the latter, namely because the PTO examiners often leave off the “consistent with the specification” portion of the rubric and thus just interpret your claim broadly.
Having two rubrics is not without its critics, but one reason for the difference is because of the presumption of validity 
that patents are given in court and are not given at the PTO. To put this in context, think of a patent as an island. The court assumes (i.e., attaches a presumption of validity) that the island’s boundaries are sufficiently far enough away from other islands (i.e., prior art) that the patent is valid. In contrast, the PTO does not (regularly) make this assumption and instead assesses whether one or more of the island’s boundaries are too close to other islands (i.e., prior art) and thus the island boundary should be brought in (i.e., the claim should be narrowed).
Interestingly, while the PTO’s technique applies to almost every patent and patent application it reviews, the PTO applies the court’s interpretation technique to expired patents. I believe that this alternative is employed because 1) an expired patent can no longer be amended by the patentee to more narrowly describe her invention, i.e., the island boundary cannot be brought in and 2) the patent was already deemed valid and was presumed valid for its lifetime. See Ex Parte Tractus Medical, Inc., Appeal 2012-000917, March 7, 2012 (“‘[I]n reexamination proceedings in which the PTO is considering the patentability of claims of an expired patent which are not subject to amendment, a policy of liberal claim construction may properly and should be applied.’”) (quoting Ex parte Bowles, 23 USPQ2d 1015, 1017 (BPAI 1991) and Ex parte Papst-Motoren, 1 USPQ2d 1655, 1656 (BPAI 1986)) (both nonprecedential).
The BPAI’s holding in Ex Parte Tractus Medical, Inc. relies on an interpretation of the claims’ terms that is refreshingly bounded by the claim language, the disclosure found in the patent, and the knowledge of a person of ordinary skill in the art at the time of the filing of the application—the same considerations that a court would use when construing the claims, which introduces some interesting considerations for patent owners and potential infringing defendants.
First, your expired patent may still have significant value and is more immune from attack than it was before it expired (i.e., you may not want to throw it in the garbage just yet). Second, there may be an opportunity for non-practicing entities (a.k.a. patent trolls) to wait until after a patent they plan on asserting in litigation expires or to acquire recently expired patents for assertion in a litigation, knowing that a reexamination may not be successful and thus settlement is more likely. And third, if your company is under threat of suit or is in the early stages of litigation, you may want to more stringently evaluate a quest to invalidate using reexamination. This last concern may not be a significant one considering the current cost of filing a reexamination when compared to the cost of litigation, or even with the increased cost under the America Invents Act. Nonetheless, if the prior art you plan to submit to the PTO is less than bullet proof, you may want to avoid a fruitless exercise (unless the other advantages of reexamination weigh in your favor).
