Kessler Doctrine Bars Patent Infringement Case Against Subsequent Product Versions

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By Tony Dutra  

March 25 --A 107-year-old doctrine fills the gap left by res judicata doctrines that would otherwise allow assertion of new claims of the same patent held not infringed in an earlier action, the U.S. Court of Appeals for the Federal Circuit ruled March 24.

The patent's licensee tried to assert method claims--voluntarily dismissed from the first case--against “essentially the same” subsequent product versions that were found not liable for infringement of apparatus claims. The court held that claim and issue preclusion doctrines would not bar a lawsuit, but the “Kessler doctrine,” allowing an adjudicated noninfringer to rely on the first decision, would.

Second Action by Licensee

Brain Life LLC is licensee of a patent (U.S. Patent No. 5,398,684) on both a method and apparatus for generating a video image from multiple source images, such as CAT, MRI and X-ray.

Its predecessor-in-interest, Medical Instrumentation Diagnostics Corp. asserted the patent against Elekta Inc.'s GammaKnife, GammaPlan and SurgiPlan products. However, before claim construction, MIDCO agreed to dismiss the complaint as to the method claims.

The Federal Circuit reversed findings leading to a $16 million award to MIDCO, as it held that the apparatus claims supported only analog-to-digital conversion with respect to a means-plus-function claim. 

In subsequent litigation of the same patent against Elekta--adding assertions against a new ERGO++ product--and other alleged infringers, the U.S. District Court for the Southern District of California construed the method claims to cover digital-to-digital conversion. But Judge Cathy Ann Bencivengo granted Elekta's motion for summary judgment on res judicata grounds.

Claim, Issue Preclusion No Bar

Judge Kathleen M. O'Malley wrote the appeals court's opinion, beginning with a review of claim preclusion.

“For claim preclusion to apply in a patent case, the alleged infringer must demonstrate that the accused product or process is 'essentially the same' as the accused product or process in the first litigation,” the court said, citing Nystrom v. Trex Co., 580 F.3d 1281, 1285, 2009 BL 190753, 92 U.S.P.Q.2d 1060 (Fed. Cir. 2009) (173 PTD, 9/10/09).

The court rejected Brain Life's argument that it could now assert the method claims against alleged infringement predating the earlier decision. But as to the possibility that post-decision product versions could infringe, the court ruled that Brain Life was not barred by claim preclusion from at least making the assertions.

And issue preclusion does not apply to method claim assertions, the court said next. “Neither party requested that any terms of the method claims from the '684 patent be construed, nor did either party move for a determination of summary judgment regarding infringement, validity, or enforceability of the method claims.”

Kessler Doctrine Rules

The court summarized these two rulings and then introduced the third related doctrine from Kessler v. Eldred, 206 U.S. 285 (1907), saying,

traditional notions of claim preclusion do not apply when a patentee accuses new acts of infringement, i.e., post-final judgment, in a second suit--even where the products are the same in both suits. Such claims are barred under general preclusion principles only to the extent they can be barred by issue preclusion, with its attendant limitations. The Kessler Doctrine fills the gap between these preclusion doctrines, however, allowing an adjudged non-infringer to avoid repeated harassment for continuing its business as usual post-final judgment in a patent action where circumstances justify that result.  


The court reviewed that case and the Federal Circuit's reference to it in MGA, Inc. v. Gen. Motors Corp., 827 F.2d 729, 3 U.S.P.Q.2d 1762 (Fed. Cir. 1987). In MGA, as here, the court said, the Kessler doctrine gave the accused infringer “rights with respect to specific products that had been held to be noninfringing, even when the specific acts of infringement would not be barred by claim preclusion because they occurred post-final judgment.”

Though Brain Life was asserting method claims now, the question is still whether the products at issue are materially the same, the court said, because Brain Life was challenging “the same allegedly infringing commercial activity” at issue in the prior proceeding.

However, in a partial reversal, the court ruled that the charges related to the ERGO++ product were not barred by any preclusion doctrine here, since that product had never been accused of infringing any '684 patent claims.

Finally, the court acknowledged that certain estoppel considerations that led to Kessler 107 years ago may not still be applicable. The court said it was bound by the holding, seemingly to deflect criticism--frequently made by the Supreme Court--that the appeals court was making a special rule for substantive patent law.

Judges William C. Bryson and Evan J. Wallach joined the opinion.

Paul Adams of the Adams Law Firm, Alburquerque, N.M., represented Brain Life. Theresa M. Gillis of Mayer Brown LLP, New York, represented Elekta.


To contact the reporter on this story: Tony Dutra in Washington at

To contact the editor responsible for this story: Naresh Sritharan at

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