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8. How are patent rights enforced?

Once a patent is granted, the owner may enforce it by bringing a patent infringement action (lawsuit) against anyone who uses the invention without the patent owner’s permission. Normally, when a patent infringement action is filed, the alleged infringer counters by attacking the validity of the patent. Patents may be held invalid on a number of grounds, such as fraud on the U.S. Patent and Trademark Office during the application period; a violation of the anti-trust laws that curb restraints of trade and monopolistic practices; or—as is most common—if an alleged infringer can show that the invention really wasn’t novel or nonobvious, that the patent examiner simply made a mistake in issuing the patent.

Assuming, however, that the patent is upheld, the court will take one of two approaches. It may issue a court order (injunction) preventing the infringer from any further use or sale of the infringing device and award damages to the patent owner. The court may instead work with the parties to hammer out an agreement under which the infringing party will pay the patent owner royalties in exchange for permission to use the infringing device.

Related terms: admissions by inventor ; breaking a patent; contributory infringement of patent; Court of Appeals for the Federal Circuit (CAFC); declaratory judgment of non-infringement, invalidity and unenforceability of patent; defenses to a patent infringement claim; doctrine of equivalents; file wrapper estoppel; infringement action; infringement of patent; intervening right; lay judge; negative doctrine of equivalents; presumption of validity; smart money; statute of limitations, infringement action; validity search.

9. When does a patent expire or otherwise come to an end?

The most common reason for a patent to come to an end is that the statutory period during which it is in force expires . For utility and plant patents, the statutory period is 20 years after the application date (21 years after the Provisional Patent Application date if one is filed). For design patents, the statutory period is 14 years from date of issuance.

Another common reason why patents expire is that the patent owner fails to pay required maintenance fees. Usually this occurs because attempts to commercially exploit the underlying invention have failed and the patent owner chooses not to throw good money after bad.

A patent may also be declared invalid (and no longer in force) if it is later shown that the patent application was insufficient, that the applicant committed fraud on the U.S. Patent and Trademark Office (usually by lying about or failing to disclose the applicant ’s knowledge about prior art that would legally preclude issuance of the patent), or that the inventor engaged in illegal conduct when using the patent—such as conspiring with a patent licensee to exclude other companies from competing with them.

Once a patent has expired for any reason, the invention described by the patent falls into the public domain: it can be used by anyone without permission and the patent owner has no more rights to the invention than any member of the public. The basic technologies underlying television and personal computers are good examples of valuable inventions that are no longer covered by in-force patents.

The fact that an invention is in the public domain does not mean that subsequent developments based on the original invention are also in the public domain. Rather, new inventions that improve public domain technology are constantly being conceived and patented. For instance, televisions and personal computers that roll off today’s assembly lines employ many recent inventions that are covered by in-force patents.