Judge Wolson Issues Key Summary Judgment Ruling on Eve of Trial in Arbutus v. Moderna

On February 2, 2026, U.S. District Court for the Eastern District of Pennsylvania Judge Joshua D. Wolson, sitting by designation in the U.S. District Court for the District of Delaware, made several key summary judgment rulings in advance of trial in Arbutus Biopharma Corporation and Genevant Sciences GmbH (collectively “Arbutus”) v. Moderna, Inc. and ModernaTx, Inc. (collectively “Moderna”), No. 1:22-cv-00252 (D. Del.).

Judge Wolson’s key rulings were:

(1) the term “for the Government” in 28 U.S.C. § 1498 means that the use of a patented product must be for the benefit of the Government itself, not the benefit of the patients who receive it, therefore precluding Moderna from asserting Section 1498 as an affirmative defense for infringement based on the vast majority of vaccines it sold to the Government in this case; and

(2) Arbutus’ removal of the term “about” in its claimed lipid ranges during patent prosecution invoked prosecution history estoppel foreclosing Arbutus from asserting infringement claims based on the doctrine of equivalents requiring Arbutus to prove infringement based on literal infringement.

The Case So Far

As we described in prior posts, on February 28, 2022, Arbutus asserted several patents directed to lipid nanoparticle (LNP) technology against Moderna alleging that Moderna’s mRNA COVID-19 vaccine and certain activities relating thereto infringed the asserted patents.

The court categorized the asserted patents as follows: The “Molar Ratio Patents” are the asserted patents that claim LNPs defined by specific lipid percentage ranges (e.g., U.S. Patent Nos. 8,058,069, 8,492,359, 8,822,668, 9,364,435 and 11,141,378); and U.S. Patent No. 9,504,651 is a patent that claims a method for formulating LNPs. Because of a prior ruling, Arbutus was forced to only assert four patents of its choosing at trial (it chose the bolded patents above).

The case proceeded over the past four years according to a customary schedule. Trial is set to begin on March 9, 2026.

Section 1498

Section 1498 provides that when a patented invention “is used or manufactured by or for the United States … the owner’s remedy shall be by action against the United States in the United States Court of Federal Claims for the recovery of his reasonable and entire compensation for such use and manufacture.” 28 U.S.C. § 1498(a).

Accordingly, as the court explained, Section 1498 allows a patent owner to recover damages for the unauthorized use or manufacture of its patented invention used or manufactured “by or for the United States.” Astornet Techs. Inc. v. BAE Sys., Inc., 802 F.3d 1271, 1277 (Fed. Cir. 2015) (emphasis in original). As the Court further indicated, a party accused of infringement in U.S. District Court can assert Section 1498 as an affirmative defense.

Here, Moderna did just that and argued that the vaccine sales it made to the Government were “for the Government” and therefore Arbutus must pursue those claims against the Government in the Court of Federal Claims. The court indicated that those vaccine sales totaled over $8.2 billion.

The court rejected this argument after interpreting the phrase “for the Government” in Section 1498 to mean that the manufacture and use of a patented product must be for the benefit of the Government itself, not the benefit of the patients who receive it.

In reaching its decision, the court heavily relied on Larson v. United States, 26 Cl. Ct. 365, 369 (1992), where the Court of Federal Claims refused to approve a Section 1498 defense where the Government paid for medical splints and casts for patients participating in certain government programs stating that “[m]edical care is provided for the benefit of the patient, not the [G]overnment.” Id.

The court further held that the affirmative defense nonetheless does apply to vaccines that the Government provided to its employees, which Arbutus alleges amounts only to 1.25% of total sales to the Government.

Doctrine of Equivalents

Another question before the court was Moderna’s motion for summary judgment that Arbutus should be precluded from asserting infringement under the doctrine of equivalents based on prosecution history estoppel.

During prosecution of one or more of the Molar Ratio Patents, Arbutus amended the claims to remove the term “about,” as shown here reflecting the amendments made during prosecution of the ‘069 patent:

1. A nucleic acid-lipid particle comprising:

(a) a nucleic acid;

(b) a cationic lipid comprising from about 50 mol % to about 65 mol % of the total lipid present in the particle;

(c) a non-cationic lipid comprising a mixture of a phospholipid and cholesterol or a derivative thereof, wherein the phospholipid comprises from about4 mol % to about10 mol % of the total lipid present in the particle and the cholesterol or derivative thereof comprises from about30 mol % to about40 mol % of the total lipid present in the particle; and

(d) a conjugated lipid that inhibits aggregation of particles comprising from about0.5 mol % to about2 mol % of the total lipid present in the particle.

The court ruled that the removal of the term “about” invoked amendment-based prosecution history estoppel and that the amendments did not fall within the tangential amendment exception.

As a result, the court held that Arbutus cannot assert infringement under the doctrine of equivalents but instead must prove its case based on a heightened literal infringement standard. The precise lipid ratios that Moderna used in its vaccines therefore becomes a crucial fact because if any of the lipid ratios of the vaccines fall outside of a claimed range, then there should be no literal infringement of that claim.

We note that the court stated that “Moderna used LNP technology with molar ratio ranges that differed slightly from those listed in Arbutus’s Molar Ratio Patents.” Given that non-infringement was not decided on summary judgment, it appears that this is an issue of fact for the jury to decide.

Invalidity

Other issues on summary judgment before the court included whether the claims were invalid based on indefiniteness. The court declined to rule on this issue because disputed facts remained and this issue will therefore be presented to the jury.

Split Ruling

This is a split ruling for the parties. On the one hand, essentially all of the over $8 billion in vaccine sales to the Government will remain in the case, creating relative damages exposure for Moderna if the asserted patents are found to be valid and infringed. On the other hand, Arbutus is now foreclosed from asserting infringement based on the doctrine of equivalents and must prove infringement based on literal infringement, which is a higher standard to satisfy.

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