How long does a patent protect someone's invention?

In general, a patent can be maintained for 20 years from the date of its first priority filing. In some pharmaceutical cases delayed by the FDA, the date can be extended somewhat.

However, a patent filed in the USA prior to June 1995 may lapse 17 years after date of ISSUE (not filing) or 20 years after date of filing, whichever is later.

Patents may also lapse because of non-payment of required maintenance fees, which vary by country.

Furthermore, a patent may be ruled completely or partially invalid for any number of reasons, making its protection questionable from that date on.


Finally, if a patent is never issued (for one reason or another) or is never filed, or is filed improperly, then it does not protect the invention at all.

On a related note: plant patents and design patents (and the like) are generally limited to much shorter periods of protection.

First answer by Wutzyerproblem. Last edit by Wutzyerproblem. Contributor trust: 443 [recommend contributor]. Question popularity: 5 [recommend question]