Patent rights in the US are acquired only after the patent is issued by the United States Patent and Trademark Office (PTO). Contrary to other forms of intellectual property, protection does not exist for patentable inventions until the patent is formally issued (Letters Patent). The PTO is responsible for determining the patentability and issuing patents. Even though inventors can prepare their own patent applications, these application are normally prepared by a certified patent specialist with engineering or scientific background.

In the US both attorneys and nonattorneys that meet the educational requirements may take the examination to become licensed patent practitioner. A nonattorney licensed to practice in patent cases by the PTO to prepare and prosecute patent applications is a Patent Agent. Patent agents can prepare, file, respond to office actions from the PTO, and participate in the amendment of the application.

After the patent is issued, the inventor acquires exclusionary patent rights for a period. Currently, utility patents filed after June 7, 1995 will expire 20 years for the date of filing.

References:
[1] Stim, R. "Intellectual Property. Patents, Trademarks, and Copyrights" West Legal Studies.
[2] Black's Law Dictionary 5th ed., (West Publishing, 1979).