When Does a Patent Expire

Inventors desiring to know "when does a patent expire" may hear the generic answer typically given in regard to patent terms, which is 20 years. However, determining the expiration date of a patent is not as simple as the blanket statement of 20 years. A patent's expiration date will be based on several factors, and in some cases it is fairly difficult to determine the patent's expiration date. In cases such as these contacting an intellectual property law attorney may be helpful, but inventors may be able to conduct research and determine the expiration date without legal assistance.

When inventors are attempting to determine a patent's expiration date certain information contained in the patent will provide guidance and help inventors more accurately establish the expiration date. The first step that needs to be taken is to determine the year the patent was filed. If the patent was filed after June 8, 1995, the patent will most likely expire 20 years after its filing date. Patents filed prior to June 8, 1995 will expire either 17 years or 20 years from the date the patent was issued. The front page of the patent is usually where the filing date can be located. If uncertainty still exists as to the date the patent was filed, an attorney could conduct a thorough review of the history of the patent.

Other factors that need to be taken into consideration when trying to answer the question "when does a patent expire" include: determining if the term of the patent was extended, if the term was shortened, and if the patent was subject to a reissue or reexamination proceeding. Whether or not the maintenance fees associated with the patent have been paid will also have an effect on the patent's expiration date. If the steps taken to determine a patent's expiration date have been unsuccessful, retaining the services of a skilled and experienced intellectual property law attorney is advised.