Serial Patent Litigation Under Hatch-Waxman Delays Affordable Generic Drugs for Years

The Hatch-Waxman Act of 1984 was designed to foster competition in the U.S. pharmaceutical market by creating an abbreviated new drug application (ANDA) pathway for generics while granting brand manufacturers patent protections and exclusivities. Central to this framework is the Paragraph IV certification process, which allows generic companies to challenge patents listed in the FDA’s Orange Book by asserting invalidity or non-infringement. Upon such a challenge, the brand manufacturer has 45 days to sue, triggering an automatic 30-month stay on FDA approval of the generic product. This stay acts as an injunction without requiring the brand to prove likelihood of success or irreparable harm, effectively delaying generic entry during litigation.

The Hatch-Waxman Act also incentivizes generics to challenge patents by awarding a 180-day exclusivity period to the first successful Paragraph IV filer, encouraging swift market entry. Ideally, this framework balances timely patent dispute resolution with incentives for generic competition. However, in practice, the process has become vulnerable to strategic abuse by brand manufacturers.

A significant source of delay arises from serial patent litigation, where brand companies repeatedly sue generic challengers over the same drug by listing new patents—often continuation or secondary patents—after initial litigation concludes. Each new patent listing can trigger a fresh 30-month stay, forcing generics into successive rounds of costly litigation. The FDA does not evaluate the validity or relevance of patents listed in the Orange Book, allowing brands to strategically add patents covering formulations, delivery devices, or dosages to prolong exclusivity.

This serial litigation imposes substantial financial burdens on generic companies, which face average Hatch-Waxman litigation costs of $6.2 million per case. In contrast, brand manufacturers can obtain continuation patents for as little as $25,000, creating an asymmetric economic dynamic that favors brands. Generics, often more capital-constrained, may delay or reduce patent challenges, effectively deterring market entry and extending brand monopolies even when the brand does not prevail in every suit.

Two prominent examples illustrate the impact of serial litigation. Allergan, now part of AbbVie, engaged in 15 years of litigation with generic manufacturers attempting to market bimatoprost, the generic version of Latisse. After initial patents were invalidated in 2014, Allergan filed successive lawsuits based on continuation patents, leading to multiple rounds of litigation and appeals. Although a jury awarded Allergan $39 million in damages in a later trial, the Federal Circuit overturned the verdict. This protracted litigation far exceeded the 30-month resolution period envisioned by Hatch-Waxman.

Similarly, Astellas’s litigation over Myrbetriq, a treatment for overactive bladder, demonstrates serial litigation’s delaying effect. After suing nine generic companies in 2016 and settling with most, Astellas filed additional lawsuits over new formulation patents, pushing back generic entry dates and extracting licensing fees. Some generics prevailed at trial in 2023, but Astellas continued to file suits over other patents, leading to at-risk launches in 2024. A recent court ruling upheld some of Astellas’s patents, but only after a decade and five litigation waves, underscoring the procedural delays independent of substantive patent validity.

The Eliminating Thickets to Increase Competition (ETHIC) Act aims to curb patent thickets by prohibiting multiple terminally disclaimed patents protecting the same drug. However, it does not address serial litigation involving continuation patents with distinct claims, which can independently trigger new lawsuits. Since drug patent thickets often consist of multiple patent families created at different times, the ETHIC Act alone cannot resolve the delays caused by serial litigation.

To preserve the balance intended by Hatch-Waxman, additional structural reforms are necessary. These could include requiring legitimate claims to be adjudicated together within defined timeframes and limiting the ability to initiate successive litigation waves based on continuation patents. Such measures would maintain valid patent protections while preventing procedural tactics that extend brand exclusivity and delay affordable generic drug availability.

Over four decades since Hatch-Waxman’s enactment, the pharmaceutical patent litigation landscape has revealed vulnerabilities that brand manufacturers exploit to delay competition. Addressing serial patent litigation is critical to ensuring timely generic entry, reducing drug costs, and promoting patient access to affordable medicines.