Willful Enough: How Halozyme Is Putting Merck on Notice

In the ongoing litigation between Halozyme, Inc. and Merck Sharp & Dohme Corp., the issue of willful patent infringement takes center stage. Filed in the District of New Jersey, Halozyme alleges that Merck’s subcutaneous (SC) formulation of KEYTRUDA® (pembrolizumab) infringes 15 of its patents covering modified human hyaluronidase PH20 enzymes, marketed by Halozyme as MDASE™.

A key aspect of Halozyme’s complaint is the allegation of willful infringement, which significantly raises the stakes by opening the door to enhanced damages and attorneys’ fees. According to Halozyme, Merck was aware of its patent portfolio—specifically through public disclosures and its own post-grant review (PGR) filings—yet proceeded to develop and commercialize SC KEYTRUDA using “berahyaluronidase alfa,” a modified PH20 enzyme with allegedly infringing amino acid substitutions.

Why Willfulness Matters

Willful infringement is more than just a finding of liability—it’s a trigger for enhanced remedies under 35 U.S.C. § 284. If a patent owner can show that the infringer acted deliberately, it can seek up to treble damages and attorneys’ fees, depending on the egregiousness of the conduct.

Halozyme is doing exactly that—arguing that Merck’s knowledge of its patents and continued commercialization of SC KEYTRUDA justifies not only compensatory damages but enhanced damages and legal costs.

The Legal Standard: SRI v. Cisco Revisited

Understanding Halozyme’s strategy requires revisiting the Federal Circuit’s important clarification of the willfulness standard in SRI Int’l, Inc. v. Cisco Sys., Inc. (Fed. Cir. 2021). In that case, the Federal Circuit overturned a district court’s JMOL (Judgement as a Matter of Law)  of no willful infringement and reinstated the jury’s willfulness verdict, making clear “The concept of ‘willfulness’ requires a jury to find no more than deliberate or intentional infringement.”

This was a crucial clarification. The court rejected the notion that a showing of “wanton, malicious, and bad-faith” conduct—language taken from Halo Electronics v. Pulse Electronics decision—is required to establish willfulness. Instead, that heightened language pertains only to the separate determination of whether enhanced damages are warranted once willfulness has been found.

In other words, willfulness is a lower bar: deliberate or intentional infringement is enough. The decision significantly impacts how district courts—and juries—analyze and determine liability and remedies in infringement cases.

Implications for Halozyme v. Merck

Halozyme’s complaint appears carefully crafted with the SRI framework in mind. By alleging that Merck knowingly infringed—armed with prior knowledge of the patents through both public sources and its own legal filings—Halozyme lays the foundation for a straightforward finding of willfulness under the clarified standard.

If the court (or a jury) agrees that Merck’s actions were deliberate, that alone could establish willful infringement. The court would then separately evaluate whether Merck’s conduct rises to the level of egregiousness necessary for enhanced damages, based on factors such as litigation behavior, motivation for harm, and the strength of the infringement case.

Takeaway

The Halozyme v. Merck case is not just a battle over biologics—it’s a timely illustration of how willful infringement is argued and analyzed post-SRI v. Cisco. The Federal Circuit has made it clear: deliberate infringement is sufficient for willfulness, and enhanced damages require an additional showing of egregious behavior. Patent holders like Halozyme are well-positioned to leverage this distinction when asserting their rights, particularly when the infringer had clear notice and continued anyway.

As this case unfolds, it will be a significant one to watch for those interested in patent litigation strategy, the evolving boundaries of willful infringement, and enforcement in the life sciences space.