The patent term in the United States was changed in 1995 to bring US 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, and since the publication of patent applications now generally occurs 18 months after filing.
Design patents, unlike utility patents, have a term of 14 years from the date of issue.
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. Extensions or other delay taken by the applicant can reduce or eliminate the extension.. The patent term may also be reduced by any disclaimer (called a "terminal disclaimer") to the patent term.
If a patent application is obvious in light of one of the applicant's existing patents, the applicant may be required by the USPTO to disclaim a part of the term. 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. If the applicant files a terminal disclaimer, then the second patent will expire at the same time as the first, the extra portion having been disclaimed. In filing the terminal disclaimer, the applicant also agrees that the second patent will only be enforceable if it and the first patent are commonly owned.
A reexamined patent expires on the day the original granted patent would have ordinarily expired.
Example: The validity of a patent (filing: Jan 1, 2000; issue: Jan 1, 2002; end: Jan 1, 2020) is challenged. The USPTO issues a more restricted patent on Jan 1, 2004. The reexamined patent is in force until Jan 1, 2020, assuming payment of all maintenance fees.
However, a terminal disclaimer does not negate Patent Term Extension that has been granted under 35 U.S.C. 156. 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.
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.
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. ruled that patents extended under Hatch-Waxman are still eligible to URAA term extension. However, patents in force on June 8, 1994 solely because of the Hatch-Waxman term adjustment are not eligible.