Patent rights last only for a limited period, and the right to sue other parties for infringing on the patent is based on this period. Thus, inventors and other patent owners may want to calculate the expiration date of their patent. This will depend on the filing date of their patent application, as well as the type of patent that they received. Patents are classified as utility patents, design patents, or plant patents.
For utility patents, which are the most common patent type, patent protection lasts for 20 years after the filing date of the patent application. (If an application for a utility patent was filed before June 8, 1995, patent protection lasts for the same 20-year period or for 17 years after the patent was granted, whichever provides longer protection.) For design patents, patent protection lasts for 14 years after the date when the patent was granted. For plant patents, patent protection lasts for 17 years after the date when the patent was granted.
The time periods above apply in standard situations, in which no circumstances arise that end the patent’s term sooner. If a patent is found to be invalid after it has been granted, patent protection will end as soon as it is found to be invalid. This may happen if a defendant in an infringement action shows that the patent that forms the basis of the lawsuit is invalid. Sometimes misconduct by the patent applicant, such as fraud against the USPTO or illegal actions while using the patent, may result in the termination of patent rights. For example, the inventor might have concealed their awareness of existing inventions (“prior art”) in their field when filing the application, which would negate the patent’s validity.
In other situations, a patent might expire when the patent owner does not keep up with the maintenance fees required by the USPTO. These must be paid at intervals of three and a half years, seven and a half years, and 11½ years. Perhaps the invention has not proved to be profitable, and the inventor no longer sees the need to pay to retain the rights to a valueless invention. They might move forward to other inventions instead.
An invention covered by an expired or invalidated patent will fall into the public domain. This means that it can be freely used without paying royalties to the inventor. However, improvements to an invention in the public domain may be covered by separate patents that were obtained later and thus remain in effect.
An inventor does not have any rights related to an invention when they have not made a written record of it. Once they have made a written record, they may have rights to the invention as a trade secret if it is kept confidential. However, they do not have patent priority at this stage because the U.S. has started using the first-to-file rule. This gives priority to the inventor who files the patent application first.
If the inventor files a provisional patent application and gets patent pending status, they probably will discourage others from duplicating their invention because they would need to stop if the patent is granted. However, the inventor does not have additional rights during this period.
The USPTO generally will publish a patent application 18 months after it is filed. The application usually is still pending at this stage, but the inventor may be able to get royalties from any entity that duplicates the invention after the application is published. They would need to prove that they eventually received a patent for the invention and that the defendant had notice of the publication.
The only right that remains after the patent expires is the right to continue bringing infringement actions based on infringements that occurred within the patent’s life. The statute of limitations will extend for a certain period after the patent expires. (Read more here about statutes of limitations in patent infringement cases.)
