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Patent Case Increases Likelihood of Intervening Rights
from Reexamination

A recent ruling in the U.S. Federal Circuit addresses how patent reexamination proceedings may affect related patent infringement litigation. The case, Marine Polymer Techs., Inc. v. Hemcon, Inc., No. 2010-1548, 2011 U.S. App. LEXIS 19602 (Fed. Cir.Sept. 26, 2011), is likely to have a significant impact on the use of reexamination proceedings in litigation. In particular, the ruling appears to increase the likelihood that accused infringers can obtain so-called “intervening rights” from a reexamination proceeding.

It was previously established by statute that intervening rights are created in accused infringers (whether or not they are a party to the reexamination or any related litigation) if the scope of the asserted patent claims that issue from a patent reexamination are not substantially identical to the original patent claims. Once created, these intervening rights may shield accused infringers against liability for otherwise infringing acts that occurred in the past (i.e., statutory intervening rights) and/or provide accused infringers with a limited right to continue to practice the asserted patent claims (i.e., equitable intervening rights).

The recent ruling in Marine Polymer states that intervening rights can be triggered by a patentee’s arguments in a reexamination, regardless of whether there is actually any patentee amendment of the language of the claims or addition of new claims. The Marine Polymer panel stated that whether intervening rights are triggered is a function of whether the scope of the claim has changed, “not merely whether different words are used.” Otherwise, a patentee could “abuse the reexamination process by changing claims through argument rather than changing the language of the claims to preserve otherwise invalid claims and, at the same time, avoid creating intervening rights as to those claims.” The patentee in Marine Polymer was held to have changed the scope of its claims—without amending them—by arguments convincing the patent examiner to adopt the district court’s erroneous claim construction and issue the claims over the otherwise invalidating prior art.

In view of Marine Polymer, patentees should keep in mind that their arguments in reexamination can (inadvertently) eliminate or limit the liability of accused infringers for acts that would otherwise constitute infringement. Accused infringers should know that forcing a patentee to argue claim scope in a reexamination includes the potential to release them from liability for otherwise infringing acts that occurred in the past and/or to obtain forward-going rights to practice the asserted claims.