Proliferating Patents, Lawsuits Stave Off Pharmas’ Generic Competitors

Why It Matters

The practice inflates drug costs, delays generic entry, and erodes the competitive balance the Hatch‑Waxman Act was designed to create, impacting patients and healthcare spenders.

Key Takeaways

• Serial litigation leverages multiple overlapping patents
• Each Hatch‑Waxman lawsuit adds ~30‑month FDA stay
• Continuation patents create patent thickets
• Generic firms face $6 M+ per lawsuit
• Potential reforms target patent‑thicket abuse

Pulse Analysis

The Hatch‑Waxman Act of 1984 was a landmark reform that streamlined generic entry by allowing abbreviated applications and patent certifications. Initially, a drug carried only a handful of patents, and successful challenges quickly lowered prices by roughly half. Over the past decade, however, manufacturers have begun filing dozens of continuation patents per product, turning a single drug into a dense patent thicket. This shift has fundamentally altered the act’s balance, giving brand‑name firms a legal lever to stall competition.

Serial litigation exploits that lever. When a generic company files an ANDA, the originator can sue on any listed patent, triggering a 30‑month stay while the case proceeds. Companies then file additional suits on other patents if the first is invalidated, creating a cascade of legal battles. Real‑world examples include AbbVie’s Humira, shielded by 105 patents for over 20 years, and Sandoz’s multi‑year fights over Bimatoprost and Myrbetriq, each round costing more than $6 million—often exceeding the drug’s development expense.

The broader impact is a prolonged monopoly that keeps drug prices high and delays savings for patients and payers. As major innovators approach patent cliffs that could shave billions from their revenue streams, the incentive to build patent thickets intensifies. Policymakers are therefore examining reforms—such as tightening continuation‑patent rules and limiting repetitive litigation—to restore the competitive intent of Hatch‑Waxman. Aligning patent protection with genuine innovation, rather than strategic market extension, will be crucial for sustainable drug pricing and access.

Proliferating Patents, Lawsuits Stave Off Pharmas’ Generic Competitors

By Sean Tu, University of Alabama School of Law · Published in Health Affairs Scholar, December 2025

The work, led by Sean Tu of the University of Alabama School of Law, appeared in Health Affairs Scholar in December 2025. It cites multiple examples of pharmas using what the authors term serial litigation to stave off would‑be competitors for years, allowing them to keep prices high.

“I’m litigating. I think the litigation is done. And then I get sued again,” Tu said. “And I do the litigation. And I think the litigation is done. And I get sued again. And it’s really problematic when it’s these patents that are really the same.”

Use of the strategy is “certainly something that we’ve watched progress probably over the last decade, decade and a half,” notes Julia Pike, the global head of IP at generics maker Sandoz. This increase comes as brand‑name drugmakers face patent cliffs that could see them lose billions in revenue in the coming years. According to analysts at William Blair, the lost exclusivity will affect assets that accounted for more than 30 % of the collective revenues from Bristol Myers Squibb, Pfizer, AstraZeneca, Novartis and Regeneron in 2024.

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A Hatch‑Waxman Loophole

Pharmas are able to employ the serial‑litigation strategy because of the way the Hatch‑Waxman Act is structured, Tu explained. Prior to that landmark 1984 legislation, generic drugmakers needed to run their own clinical trials in order to get the FDA’s nod to go to market, even when a brand‑name version of their product had already been approved.

The act removed the need for this duplicate effort by requiring the sponsor of the original drug to list all patents related to it with the FDA. Generic companies can then file an Abbreviated New Drug Application (ANDA) with the agency that includes certifications regarding each of the relevant patents. These certifications might note that a patent is expired, for example, or assert that it is invalid.

The brand‑name drugmaker then has an opportunity to sue for patent infringement. Doing so triggers a 30‑month stay on the FDA’s ANDA decision and engages the generics company in a costly legal battle.

The act worked as intended for about two decades after its passage, Tu said.

“You would see one or two patents per drug. People would challenge these patents. They would invalidate them. And then they would be able to go on the market, and the prices would drop by, like, 50 % the next day” due to the new competition.

But then, “in 2010, you saw this real huge uptake in the just number of patents per drug,” Tu noted—a trend he’s previously documented. Many of these are continuation patents, meaning that they’re essentially identical to an existing patent. These are allowed for cases in which companies want to get a product to market quickly, and thus elect to file a relatively narrow and easily‑defended patent initially, with the option to file a broader version later.

With multiple continuation patents on the books for a single drug, pharmas can choose to sue a generics maker for infringing one, and then, if the second company successfully defends against the suit, sue again under a different patent.

“If we stop competition, that’s a win for brand companies, right? That means that we’re going to have higher drug prices for longer periods of time,” Tu said. “How do I get less competitors? I make it riskier. I make it more expensive. I force them to come on the market later. All of that I can do through patents.”

Illustration: a machete with tip in ground outdoors

AbbVie’s blockbuster Humira held 105 patents, shielding the anti‑inflammatory drug from biosimilar competition for more than 20 years. Proposed reforms could help prevent companies from extending exclusivity with such patent thickets.

December 18, 2024 – 4 min read

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Costs Pile Up

Pike said the uptick in continuation patents and serial litigation is a costly trend for generics companies like hers. She cited an industry‑group estimate that each round of Hatch‑Waxman litigation costs more than $6 million. “So you can imagine if we’ve been sued three, four, five times in a row, that accumulates fairly quickly,” she said.

That’s not a hypothetical for Sandoz. In its attempt to market a generic version of Allergan’s Bimatoprost (a medication for glaucoma and high eye pressure), “We’ve been in four waves of litigation on that case since 2011. And that case continues,” Pike notes.

Sandoz was also one of several generic makers embroiled in litigation with Astellas over the right to make their own versions of the over‑active bladder drug Myrbetriq, a story cited by Tu and his colleagues as an example of the serial‑litigation strategy. Astellas has so far filed five rounds of lawsuits over the drug, and of the original nine companies vying to make generics, all but two have settled, including Sandoz.

“It’s a textbook example of serial patent litigation,” Pike said. “It’s not an Astellas strategy. It’s a broader industry strategy.”

Astellas did not respond to a request for comment on this story.

The cost of defending such lawsuits outstrips the cost of developing a drug, Pike noted. “Before you’ve even set foot in the U.S., you’re anticipating that the cost of developing that product is going to double just because of the first round of litigation.”

“People say, ‘oh, this guy doesn’t like patents,’” Tu said of himself. “That’s not true. Patents are very effective at promoting innovation… But your patents shouldn’t last forever. And we’re asking the patent system to do something now that it was never intended to do, which is extend monopoly power.”

Illustration: brain‑related graphic

Brand pharmas not only leverage ancillary patents but sometimes hide or misrepresent information to the U.S. patent office in order to extend market exclusivity and high prices.

January 8, 2024 – 5 min read