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Issue Preclusion Means One Strike and You Are Out

While issue preclusion means one strike and you are out, a court might need to call a few balls before calling the strike that ends the case.

In Horizon Medicines LLC, et al. v. Dr. Reddy’s Laboratories, Inc. et al., No. 15-cv-3324, D.I. 468, 17 (D.NJ Feb. 24, 2022), Judge Stanley Chesler of the District of New Jersey held that two Orange Book (OB)-listed patents covering Vimovo® (esomeprazole magnesium; naproxen) were invalid for lack of written description. The holding was based on issue preclusion from an earlier Federal Circuit decision addressing to two related OB-listed patents having different claims. But it took defendant Dr. Reddy’s Laboratories (“DRL”) two unsuccessful summary judgment motions before getting it right on the third try.

The lessons from this saga are threefold: (1) persistence pays off, (2) factual analyses win the day, and (3) differences in claim language should be made meaningful, not illusory.


In 2011, Horizon Pharma (now Horizon Medicines LLC, “Horizon”) sued DRL and Mylan in Hatch-Waxman litigation for filing ANDAs with Paragraph IV certifications to the OB-listed patents for Horizon’s Vimovo® (esomeprazole magnesium; naproxen). Following a bench trial, Judge Mary Cooper of the District of New Jersey found the patents to be valid and infringed. Defendants appealed, and the Federal Circuit invalidated the patents for lack of written description. Nuvo Pharm. Et al. v. Dr. Reddy’s Labs., et al., 923 F.3d 1368 (Fed. Cir. 2019).

At the time of the Appeal, the OB-listed patents were owned by Nuvo Pharmaceuticals (“Nuvo”). And Nuvo was not idly standing by waiting for the outcome of the appeal, rather, it diligently sought additional patents by prosecuting continuation patent applications that were filed based on one of the two OB-listed patents pending in the appeal. The continuation applications issued in the ensuing years and were, too, listed in the OB. In 2015, Horizon and Nuvo again sued DRL, this time asserting the most recently issued Nuvo OB-listed patents.

As with all continuation applications, all the Nuvo OB-listed patents shared the same specification. The only key difference between the invalidated patents and the more recently issued OB-listed patents was the limitation of a “non-enteric film coating” (in the more recent continuation patents). It turned out that the claims were too similar, which led to their demise. Following two denied motions for summary judgment, DRL filed one more asserting that the more recently issued Nuvo OB-listed patents were invalid for lack of written description based on issue preclusion. In an unpublished opinion, U.S. District Court Judge Stanley Chesler granted DRL’s motion. In Judge Chesler’s words, plaintiff “failed to explain how any differences in claim wording change the invalidity analysis.” Horizon Medicines LLC, et al. v. Dr. Reddy’s Laboratories, Inc. et al., No. 15-cv-3324, D.I. 468, 17 (D.NJ Feb. 24, 2022).

Lesson #1: Persistence Can Pay Off

In the seven years of litigation, DRL actually filed five motions for summary judgment, showing that persistence pays off.

First motion: DRL filed its first motion for summary judgment in 2016, a year after the complaint, moving for invalidity of the original two Orange Book-listed patents. While the district court denied this motion, the Federal Circuit ultimately invalidated these two patents in 2019.

Second motion: DRL filed its second motion in 2018, arguing two of the asserted patents were invalid for indefiniteness. The district court agreed, invalidating those patents.

Third motion: DRL filed its third motion in 2019, after the Federal Circuit’s holding on the original two Orange Book-listed patents. DRL argued that issue preclusion required that the remaining patents be found invalid for lack of written description. The district court denied the motion without prejudice because there were literal differences in the claims between the asserted patents and the patents invalidated by the Federal Circuit, and claim construction had not yet occurred.

Fourth motion: DRL filed its fourth motion a year later in 2020, after claim construction was completed, arguing that with the claims construed, no factual dispute remained and that any differences between the claims were “immaterial.” Unfortunately, the district court disagreed, holding that “[p]erhaps DRL can demonstrate that such differences indeed have no material impact on the written description analysis – but such a demonstration remains to be attempted.” D.I. 340 at 4.

Fifth motion: DRL filed its fifth (and ultimately successful) motion in 2021 after additional expert discovery relating to the scope of the claims, with which DRL had amassed the evidence it needed. Judge Chesler held that “Plaintiffs have neither demonstrated any material difference between the sets of patents that could change the written description analysis, nor have they raised any material factual dispute as to whether there is any material difference between the sets of patents.” D.I. 468 at 16. After successfully fending off DRL two prior times, plaintiffs’ luck had run out.

The takeaway is that persistence pays off.

Lesson #2: Show the Court—Don’t Just Tell the Court

A recurring theme in Judge Chesler’s opinions was his repeated complaint that he was not being shown why each side was correct.

DRL asserted in its fourth motion that any differences in the claim language between the patents that were invalidated by the Federal Circuit and the patents still at issue were “immaterial.” In denying DRL’s fourth motion, Judge Chesler remarked that DRL “does not support this assertion with any analysis.” D.I. 340 at 4.

In granting DRL’s fifth motion, Judge Chesler remarked that while “Plaintiffs offer the conclusory assertion that the contrary conclusions of their experts are sufficient to raise a factual dispute, … Plaintiffs’ brief cites no particular expert statement” in support of that conclusion. D.I. 468 at 11. A vague citation to “fourteen pages of expert reports” was not sufficiently clear to the judge that there was a genuine dispute of fact (“This Court has no doubt that there can be cases in which such factual disputes may arise, but this is not one of them.”). Id.

The takeaway is that you are better off trading in conclusory statements for a clear factual analysis supported by the record.

Lesson #3: Differences in Claim Language Should Be Meaningful

A good strategy for building a robust patent portfolio is to include many patents with claims directed to various aspects of an invention. This strategy offers at least some level of patent protection even when certain patents in the portfolio are invalidated. This strategy only works, however, if the differences among the claims of the patents are sufficiently meaningful to establish actual and not just illusory differences in claim scope.

In this case, the original Orange Book-listed patents had claims directed to uncoated dosage forms, which were found to lack written description support. The follow-on claims were directed to “non-enteric film coat[ed]” dosage forms. This difference was sufficient to result in two separate denials of DRL’s motions—the first before claim construction, and the second before any meaningful evidence of whether a person of ordinary skill in the art (POSA) would equate an uncoated dosage form from one that has a non-enteric film coating. But by the final motion, DRL developed expert testimony that there was no meaningful difference to a POSA between a dosage form without a coating and one with a non-enteric film coating.

While Nuvo had the opportunity to develop a factual dispute through its own experts, Judge Chesler found that Nuvo did not sufficiently explain why there was such a factual dispute. Was there such evidence? As this article is posted, Nuvo still has time to appeal if it thinks Judge Chesler got it wrong and that the Federal Circuit will review de novo. Stay tuned.

The takeaway is that it is critical to build a robust patent portfolio with several patents, each with claims written in a way that meaningfully distinguishes the scope of one claim from the scope of another. This significantly improves the likelihood that condemnation of one patent in a family will not necessarily flow to the other family members.