The 30-month stay explained

Between 1992 and 2000, brand drug companies listed a new patent with FDA after a generic application was already on file in eight instances, according to a Federal Trade Commission study published in July 2002³. Each new patent set off a second automatic pause on generic approval. The extra delay beyond the first pause ranged from 4 to 40 months. In all four of those cases that reached a court decision, the later patent was found invalid or not infringed.

Congress responded in December 2003 by limiting each generic application to one such pause. The rule it left in place, the 30-month stay, still decides the earliest date many generics can be approved when a brand company sues over a patent.

Outside patent law the stay gets little attention, yet it is one of the more consequential pieces of the 1984 Hatch-Waxman Act. This explainer covers how it is triggered and ended, why Congress chose 30 months, what the FTC found when it studied the stays, and how the 2003 changes work.

How the stay is triggered

Its mechanism sits in section 505(j)(5)(B)(iii) of the Federal Food, Drug, and Cosmetic Act. A generic applicant that files a Paragraph IV certification, asserting that a listed patent is invalid or will not be infringed, must notify the brand. The generic's approval "shall be made effective immediately" unless the patent owner sues within 45 days of receiving that notice, according to 21 U.S.C. 355(j)(5)(B)(iii)¹.

If the suit is filed in time, approval waits until "the expiration of the thirty-month period beginning on the date of the receipt of the notice," or a shorter or longer period if a court finds that "either party to the action failed to reasonably cooperate in expediting the action," the statute says. The notice clock and certification rules are covered in GxRadar's explainer on Paragraph IV certifications.

FDA's own description is brief. The postponement "gives the brand product sponsor and patent holder a prescribed amount of time to assert patent rights in court before a generic competitor is approved and can market the drug," the agency's patent certifications page says⁹. FDA can keep reviewing the application during the stay and issue a tentative approval. The stay controls when approval can take effect, not whether review continues.

Source: 21 U.S.C. 355(j)(5)(B)(iii) and (j)(5)(F)(ii)¹. FDA's implementing rule is 21 CFR 314.107². The new chemical entity provision is described in GxRadar's piece on the four-year door for generics.

A stay is not automatic in the sense of applying to every patent. Since 2003, only a suit on a patent whose information was submitted to FDA before the generic application was filed can trigger it. A brand can still sue on a later-listed patent, but that suit does not pause FDA approval.

Why 30 months

In 2002 the FTC tested whether the number fit reality. Thirty months "historically has approximated the time required for FDA review and approval" of challenged applications and for court resolution, the 2002 study found³.

Cases were getting longer, the study warned, as brands asserted more patents. Before 1998, the brand alleged infringement of three patents in only 1 of the 9 blockbuster drugs where it sued the first generic applicant. From 1998 on, it alleged three or more in 5 of 8. As of June 1, 2002, in 6 of the 7 cases pending more than 30 months without a district court decision, the brand had alleged three or more patents.

What the FTC found in 2002

To build the study, the FTC used its subpoena power to collect records on generic applications seeking entry before patent expiration, which it found had grown from 2 percent of generic applications in the 1980s to about 20 percent from 1998 to 2000. Brand companies sued the first generic applicant for 75 of the 104 drug products studied, or 72 percent, the study reports³. Median net sales for the products that drew a suit were $190 million a year; most of the 29 products with no suit had sales under $100 million.

Generic applicants prevailed in 73 percent of the cases in which a court resolved the patent dispute. The FTC's first legislative recommendation was to "permit only one automatic 30-month stay per drug product per ANDA to resolve infringement disputes over patents listed in the Orange Book prior to the filing date of the generic applicant's ANDA."

FDA then quantified the cost of multiple stays for six drugs drawn from the FTC's data, in its October 2002 proposed rule⁴. FDA counted the two gabapentin dosage forms as one drug and dropped a seventh case it said the rule would not address.

Source: FDA, 67 FR 65448, Table 2⁴. *FDA's note: potential period, actually shorter because of a court decision. Terazosin's stay periods did not overlap. All six are now long-generic; gabapentin's price history is on its GxRadar drug page.

The 2003 fixes, by rule and by statute

FDA moved first. Its final rule, published June 18, 2003, and effective Aug. 18, 2003, "allows only one 30-month stay per ANDA or 505(b)(2) application; it does not permit multiple 30-month stays," the rule says⁵. The agency wrote that its earlier regulations "permitting multiple 30-month stays have led to considerable delays in the approval of generic drugs," a consequence "not intended either by Congress or by FDA."

Congress wrote the limit into law months later. The Medicare Prescription Drug, Improvement, and Modernization Act of 2003⁶, signed Dec. 8, 2003, tied the stay to patents whose information was submitted before the generic application. The same law let a sued generic applicant counterclaim to correct or delete a brand's patent listing, and required brand and generic companies to file Paragraph IV settlement agreements with the FTC and the Justice Department within 10 business days. GxRadar covers the rest of that law in the Medicare Modernization Act of 2003 and the settlement filings in pay-for-delay settlements.

The stay today

A great many products are exposed. FDA's list of drug products facing at least one Paragraph IV challenge had 1,650 entries in its Oct. 27, 2026 update¹⁰, each a product for which a suit, and so a stay, was possible.

Much still turns on what brands list. The FTC's 2023 policy statement says a brand may benefit from a 30-month stay "regardless of whether a court ultimately finds the patent at issue is valid or infringed by the competing product," in its text⁷, and the agency has since disputed hundreds of Orange Book listings, as described in GxRadar's piece on Orange Book listing challenges.

The first generic to file a Paragraph IV challenge may also earn 180 days of exclusivity, so the stay and the exclusivity together often decide how many versions reach pharmacies in a generic's first months. The 30-month length itself dates to the 1984 law. CRS has flagged one option for lawmakers: whether "the 30-month stay should apply only to certain patent types (e.g., active ingredient patents)," its January 2026 report says⁸.