One needs to check several things before one can determine when a patent will expire or has expired.
Determine the Patent term: First, you need to determine the patent's filing date and whether it claims priority to any earlier U.S. application. Most utility patents today have a term that expires 20 years from the earliest filing of the patent. However, patents that were pending at the USPTO before June 8, 1995 are subject to a dual term that makes the patent term the longer of: (1) 20 years from the patent's earliest filing date, or (2) 17 years from the patent's issue date. For example, if an application's earliest filing date is May 1, 1995, and it issued on May 1, 2000, the patent would be subject to the dual term determination. The 20 year term calculation would lead to an expiration date of May 1, 2015, but the 17 year from issue term calculation would lead to an expiration date of May 1, 2017. Thus, the longer 17 year term from issue would apply. The earliest filing date can be prior to the patent's actual filing date if it is a continuation, continuation-in-part, or divisional application of an earlier U.S. patent application. Also, the earliest filing date could include the international filing date if the priority application was filed under the Patent Cooperation Treaty (PCT). The earliest filing date does not include an earlier provisional filing date if the patent claims priority to the provisional.
If you are dealing with a design patent, its expiration date is determined from its date of issuance, not the earliest filing date. See our earlier post on this subject. In sum, design patents granted on applications filed before May 13, 2015 will have a 14 year term, and those granted on applications filed on or after May 13, 2015 will have a 15 year term.
Check Patent Term Adjustment: Starting in May 2000, patents issuing from the USPTO were eligible for patent term adjustment (PTA). Around this time, the USPTO recognized that many long delays in prosecution were due to backlogs at the USPTO, and not due to the fault of the applicants. The USPTO simply had too much work on its hands. To make sure that applicants (with a 20 year patent term from the earliest filing date) were not adversely affected by the USPTO backlog, the patent statute (35 USC 154) was amended to provide for PTA in which the USPTO would determine a number of days that would be added to patent's term. The length of PTA can be seen on the face of issued patents, usually below the patent assignee. The number of PTA days should be factored into your determination on the patent's expiration date. It should be noted that the USPTO's PTA calculation is not always accurate, and an applicant may request for reconsideration of the PTA within two months of the grant date of the patent.
Check Terminal Disclaimers: Some patents may expire prior to their expected patent term because of a terminal disclaimer. A terminal disclaimer may be filed in a child application (e.g., an application claiming priority to an earlier filed application) to avoid a double patenting rejection. When the terminal disclaimer is filed, the patent term of the child patent that would last beyond the expected expiration date of the parent patent is disclaimed or given up. Thus, you must check for terminal disclaimers filed during the patent's prosecution to determine if the patentee has disclaimed a portion of its term. Terminal disclaimers are often referenced on the face of issued patents these days, but it is important to check a patent's file history to be certain whether one has been filed and the true time period of the disclaimer.
Check Fees Online: After issuance, utility patents require the payment of additional maintenance fees at 3.5, 7.5 and 11.5 years from the patent's issue date. If a patentee fails to pay the required maintenance fees prior to the expiration of a grace period (essentially by 4, 8 and 12 years from issuance), the patent will expire for failure to pay the required fees. One can check the maintenance fee status of an issued patent using the USPTO's maintenance fees web page. Importantly, design patents do not require maintenance fees after issuance.
Overall, determining a patent's expiration can be a tricky endeavor. It may seem simple, but there are often many nuances (and other particular ones not listed above) that can effect a patent term or whether it has expired. We recommend that you consult with counsel if you have an important legal issue that could be impacted by whether a patent has expired or not.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
