Patent term extension

In the United States, under current patent law, the term of patent, provided that maintenance fees are paid on time, are:

  • For applications filed on or after June 8, 1995,[1] the patent term is 20 years from the filing date of the earliest U.S. application to which priority is claimed (excluding provisional applications).[2]
  • For applications filed before June 8, 1995 and for patents that were still in force on June 8, 1995, the patent term is either 17 years from the issue date or 20 years from the filing date of the earliest U.S. or international (PCT) application to which priority is claimed (excluding provisional applications), the longer term applying.[3][4]

The patent term in the United States was changed in 1995 to bring U.S. patent law into conformity with the World Trade Organization's Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPs) as negotiated in the Uruguay Round. As a side effect, it is no longer possible to maintain submarine patents in the U.S., since the patent term now depends on the priority date, not the issue date.

Design patents, unlike utility patents, have a term of 14 years from the date of issue.[5]


The original patent term under the 1790 Patent Act was decided individually for each patent, but "not exceeding fourteen years".[6] The 1836 Patent Act (5 Stat. 117, 119, 5) provided (in addition to the fourteen year term) an extension "for the term of seven years from and after the expiration of the first term" in certain circumstances.[7] In 1861 the seven year extension was eliminated and the term changed to seventeen years (12 Stat. 246, 249, 16). The signing of the 1994 Uruguay Round Agreements Act[8] then changed the patent term from seventeen years from the date of issue to the current twenty years from the earliest filing date.

Year Validity
-1789 -
1790–1835 14
1836–1860 21
1861–1994 17
1995- 20

Adjustments possible under current law

If the United States Patent and Trademark Office fails to examine a patent application in time (deadlines for various steps are different), the patent term may be extended.[9] Extensions or other delay taken by the applicant can reduce or eliminate the extension.[10] The patent term may also be reduced by any disclaimer (called a "terminal disclaimer") to the patent term.

A reexamined patent expires on the day the original granted patent would have ordinarily expired.

Example: The validity of a patent (filing: January 1, 2000; issue: January 1, 2002; end: January 1, 2020) is challenged. The USPTO issues a more restricted patent on January 1, 2004. The reexamined patent is in force until January 1, 2020, assuming payment of all maintenance fees.

The Patent Cooperation Treaty provides a process for a patent filing to claim the priority date of an earlier foreign patent application. Within one year of filing a patent application in one country, an international patent application (which "designates" certain other countries, by default all contracting states) can be made. This holds the original priority date and starts the 20-year validity clock, while allowing the actual patent application in the designated countries (and the associated expenses) to be deferred an additional 20 months.[11] Such a patent would expire earlier than 20 years after U.S. filing.

Terminal disclaimer

If any claim of a pending patent application is obvious in light of at least one claim of the applicant's issued patents, the applicant may be required by the USPTO to disclaim a part of the term of the pending application. For example, an applicant's patent A expires on December 24, 2000. The applicant filed another patent application two years later. Under some conditions, the second patent might expire later than the first (based upon the respective earliest claimed priority dates). If the applicant is required to file, and does file, a terminal disclaimer in the later filed patent, then the later filed patent will expire at the same time as the earlier filed patent, the extra term having been disclaimed ("terminal disclaimer"). In filing the terminal disclaimer, the later filed patent and the earlier filed patent must be, and remain, commonly owned.

The terminal disclaimer is not always carved in stone. After the Uruguay Round Agreements Act of 1994 (URAA), some patents with terminal disclaimers are eligible to a term adjustment because their referenced patents received a term adjustment because of the URAA. This has been discussed in the Manual of Patent Examining Procedure:

To determine the "original expiration date" of a patent subject to a terminal disclaimer, it is generally necessary to examine the language of the terminal disclaimer in the patent file history. If the disclaimer disclaims the terminal portion of the term of the patent which would extend beyond the expiration date of an earlier issued patent, then the expiration date of the earlier issued patent determines the expiration date of the patent subject to the terminal disclaimer. Before June 8, 1995, the terminal disclaimer date was printed on the face of the patent; the date was determined from the expected expiration date of the earlier issued patent based on a seventeen year term measured from grant. When 35 U.S.C. 154 was amended such that all patents (other than design patents) that were in force on June 8, 1995, or that issued on an application that was filed before June 8, 1995, have a term that is the greater of the "twenty year term" or seventeen years from the patent grant, the terminal disclaimer date as printed on many patents became incorrect. If the terminal disclaimer of record in the patent file disclaims the terminal portion of the patent subsequent to the full statutory term of a referenced patent (without identifying a specific date), then the date printed on the face of the patent is incorrect when the full statutory term of the referenced patent is changed as a result of 35 U.S.C. 154(c). That is, the referenced patent's "twenty year term" is longer than the seventeen year term. In such a case, a patentee may request a Certificate of Correction under 37 CFR 1.323 to correct the information printed on the face of the patent. However, if the terminal disclaimer of record in the patent file disclaims the terminal portion of the patent subsequent to a specific date, without reference to the full statutory term of a referenced patent, then the expiration date is the date specified. Several decisions related to disclaimers are posted in the Freedom of Information Act (FOIA) section of the USPTO Internet site ([12]

However, a terminal disclaimer does not negate Patent Term Extension that has been granted under 35 U.S.C. 156.[13] In a pharmaceutical patent dispute, Teva argued that Wyeth’s patent on zaleplon drug products (Sonata) had expired because of a terminal disclaimer. Wyeth (and its exclusive licensee King) argued that patent’s term was ongoing because of a Patent Term Extension due to FDA regulatory review delay. Under 35 U.S.C. 156(a), the term of a patent "shall be extended" after a series of provisions are satisfied. The district court found the language of the statute unambiguous and gives the court "no discretion".

Thus, if the enumerated conditions are satisfied, the patentee is entitled to a term extension calculated pursuant to Section 156. Teva's motion to dismiss was consequently denied because "a terminally disclaimed patent is eligible for extension under [Section] 156." The case is interesting because the patentee in the first instance had expressly disclaimed term subsequent to 2003 to get the patent granted. However, the holding of this case does not apply to Patent Term Adjustment granted under 35 U.S.C. 154. Such term adjustments will be subject to any terminal disclaimer that has been filed.[14]

There is now a similar case wherein a company was given extension under S.156 and the generic entrant arguing against such extension between Merck and Hi-tech for a drug called "dorzolamide" (TRUSOPT/COSOPT). Here too, the first company (Merck) had filed a standard form terminal disclaimer. This patent was later given an extension and became the crux of the litigation.[15]


The Drug Price Competition and Patent Term Restoration Act (Hatch-Waxman Act) of 1984 provides patent holders on approved patented products with an extended term of protection under the patent to compensate for the delay in obtaining Food and Drug Administration (FDA) approval.

Merck & Co., Inc. v. Hi-Tech Pharmacal Co., Inc.[16] ruled that patents extended under Hatch-Waxman are still eligible to URAA term extension. However, patents in force on June 8, 1995 solely because of the Hatch-Waxman term adjustment are not eligible.

See also


Further reading

  • For a detailed description of the laws and rules governing patent terms in the U.S., see the Chapter 2700.

External links

  • § 154 - Contents and term of patent; provisional rights
  • Manual of Patent Examining Procedure (MPEP), USPTO
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