Patent Term
For medical device companies, the patent clock and the regulatory clock run at the same time. By the time a Class III device receives premarket approval, clinical investigation and FDA review may have consumed a meaningful share of the patent term. 35 U.S.C. §156 allows the term of a qualifying patent to be extended to restore part of that time. The provision is narrower for devices than many teams assume, and the decisions that determine its value are made long before approval.
Section 156 applies to a patent that claims a product, a method of using the product, or a method of manufacturing it, where the product was subject to a regulatory review period before commercial marketing. For a medical device, that review must have occurred under section 515 of the Federal Food, Drug, and Cosmetic Act — the Premarket Approval (PMA) provision, which also includes the product development protocol route. The USPTO's Manual of Patent Examining Procedure states directly that a regulatory review period under section 510(k) does not give rise to eligibility for patent term extension. The MPEP also notes that devices reviewed under the Humanitarian Device Exemption are considered to be reviewed under section 515.
De Novo classification is a separate pathway under section 513(f)(2) of the Act, which places novel devices in Class I or Class II. Because it is not review under section 515, it falls outside the statutory basis for device extensions. In practical terms, patent term extension is a tool for devices reviewed under section 515, including PMA, product development protocol, and HDE routes, which are generally Class III products.
Two further conditions matter. The approval must be the first permitted commercial marketing or use of the product under the provision of law under which the review occurred, and the patent must not have been extended under section 156 before.
For devices, the regulatory review period has two phases. FDA's regulation at 21 CFR 60.22 defines the testing phase as beginning on the date a clinical investigation on humans begins and ending on the date the PMA, or a notice of completion of a product development protocol, is initially submitted under section 515. Where an investigational device exemption is required, the clinical investigation begins on the effective date of the IDE; where no IDE is required but institutional review board approval is, it begins on the IRB approval date. The approval phase runs from initial submission of the PMA to the date the application is approved.
The extension is not simply equal to that period. Under the statute and the calculation set out in MPEP 2758, several reductions apply. Any part of the review period that occurred on or before the date the patent issued is excluded. Any period during which the applicant did not act with due diligence is subtracted. Only one-half of the remaining testing phase is counted, while the remaining approval phase counts in full. The result is then subject to two ceilings: the patent term remaining after approval, plus the extension, may not exceed fourteen years; and for a patent issued after September 24, 1984, the extension may not exceed five years.
The ceilings can control the result. A patent with substantial term remaining on the approval date may gain little or nothing under the fourteen-year limit, even after a long clinical program, while a patent issued late in development loses the review time that preceded its issuance.
Only one patent may be extended for a regulatory review period for any product. If applications are filed on more than one patent based on the same product, the USPTO will provide a period, usually one month, for the applicant to elect the patent to be extended; according to the MPEP, if no timely election is made, the certificate will issue for the patent with the earliest date of issuance. The reverse is also true: a patent may be extended only once, so a patent that covers several approved products must be allocated to one of them.
The rights available during the extension are also narrower than the original patent. Section 156(b) limits the extended rights, for a patent claiming a product, to uses approved for the product. An extended patent does not carry its full original scope into the added years.
The application must be submitted by the owner of record of the patent or its agent within the sixty-day period beginning on the date the product received permission for commercial marketing. The MPEP is explicit that day one of that period is the approval date itself, not the following day, and that the statutory period is not extendable and cannot be waived or excused. A regular application also cannot be filed before approval. A team that starts the analysis when the approval letter arrives has roughly eight weeks to do all of the work.
A related provision addresses patents that would expire while review is still underway. Section 156(d)(5) permits a request for interim extension, filed in a window beginning six months and ending fifteen days before the patent is due to expire, where the owner reasonably expects the approval phase of review to extend beyond the patent's expiration. Interim extensions are granted in one-year increments. If that window is missed, the patent may expire before approval, and an expired patent cannot be extended.
Several practical consequences follow for companies on the PMA pathway.
The regulatory chronology becomes evidence. The calculation depends on the IDE effective date, the initial PMA submission date, and the approval date, and due diligence can be questioned. A contemporaneous record of submissions and FDA correspondence makes the application easier to prepare and support.
Claim coverage must match the approved device. The extension attaches to a patent that claims the approved product, a method of using it, or a method of manufacturing it. The MPEP notes case law holding that claims must include some physical structure of the device for a patent to claim the product. A portfolio intended to benefit from extension should include at least one patent whose claims read squarely on the device as approved, not only on an early prototype. Continuation practice during the clinical program can help keep claims aligned with the final design.
Patent selection is a modeling exercise. Because only one patent can be extended, the choice among candidates turns on remaining term, the fourteen-year and five-year ceilings, the portion of the review period that preceded each patent's issuance, and the strength and breadth of each patent's claims. The patent that produces the longest extension is not necessarily the one that provides the most useful protection, particularly given that extended rights are limited to approved uses.
For companies based outside the United States, filing mechanics deserve early attention. The application must come from the owner of record or its agent, so ownership records, agency arrangements, and access to the regulatory record are better confirmed before approval.
Patent term extension is unavailable for devices marketed through 510(k) clearance or De Novo classification, and it will not strengthen claims that do not cover the commercial product. For PMA devices, however, it can add up to five years of term to the patent that most closely protects that product. Companies moving a Class III device through clinical investigation may find it useful to review with patent counsel which patents are positioned to qualify, how the calculation is likely to come out, and what records and claim coverage should be in place before approval. This article provides general information and is not advice on any specific situation.