Patents, unlike trademarks and somewhat dissimilar from copyrights, have a fixed term of duration such that it is not only commonplace for a patent to expire, but inevitable. Trademarks persist for as long as a mark or trade dress is used in commerce and the requisite fees are paid, and though copyrights do technically expire, they enjoy a much longer term that has been renewed time and again by Congressional act. Yet patents are in practice necessarily granted for limited times.

Generally speaking, different types of patents have different lengths but the standard utility patent expires 20 years from the date the patent issues, or from the date of the earliest application to which the current application references. At this point, one might be asking why an applicant would reference and earlier application and thereby shorten the amount of time he has to enjoy patent protection. Yet sometimes this is necessary to obtain the patent, especially if failure to mention the earlier application would result in the existence of prior art that would prevent you from obtaining any kind of patent rights at all. In other words, by claiming that earlier registration, the applicant also avoids the potential problem of prior art that arose between the initial application and the current application.

Given that the term of patent protection is relatively short as compared to other forms of intellectual property protection, and given that the process of prosecuting a patent can be extremely time consuming, the United States Patent and Trademark Office (USPTO) is empowered make certain exceptions when it comes to patent terms. Generally speaking, the USPTO also guarantees that the prosecution process will not take more than three years time. However, the USPTO can also grant extensions of the patent term for delays in the prosecution of the patent. Specifically, if prosecution of the patent is delayed due to legal proceedings, orders or appellate review by the BPAI or a Federal court of competent jurisdiction, an additional day will be added to the term of the patent to account for each day of delay. The USPTO is also empowered to extent the patent term where regulatory scrutiny from the Federal Food Drug and Cosmetic Act or the has lead to a delay in the products ability to sell on the open market. Design patent terms are shorter than utility and plant patent terms, but were recently extended from 14 years to 15 years in recent legislation signed by President Obama. That legislation also included other reforms to design patent laws, particularly with respect to foreign patent application issues.

Like most legal issues, what might seem like a simple question deserving of a simple answer is actually potentially very complicated. Patent term is 20 years, but issues of earlier applications being mentioned, extensions for delays at the patent office, and distinctions between different types of patents can complicate the issue. As always, the assistance of a licensed patent attorney is helpful for grappling with this and other patent issues.