When Do Patents Begin and How Long Do they Last?

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Patent protection doesn’t last forever. Indeed, patents are typically the shortest lived of all forms of intellectual property protection. When a patent expires, the invention described by the patent falls into the public domain: it can be used by anyone without permission from the owner of the expired patent. The basic technologies underlying television and personal computers are good examples of valuable inventions that are no longer covered by in-force patents.

How long a patent lasts depends on when the application was filed with the U.S. Patent and Trademark Office.

Patents Filed Through June 17, 1995

For U.S. patents filed through June 17, 1995, the patent lasts for 17 years from the date the patent is issued, provided that the fees necessary to keep the patent in force (maintenance fees) are paid. 

Patents Filed After June 17, 1995 

For patent applications filed after June 17, 1995, the patent last 20 years from the date of filing. Since applications typically take one to three years to process, most patents filed after 1995 have an effective duration of 17-19 years.

Design Patents

Design patents, which protect only the ornamental appearance of an article, last for fourteen years from the issue date. 

Patent Extensions

In some cases patents can be extended for up to five years. Examples include where there have been delays in issuing the patent due to interference proceedings, appellate review of the patent’s validity, or failure of the U.S. Patent and Trademark Office to issue the patent within three years.

New Developments May be Patentable

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.