When a patent is issued under the seal of the United States Patent and Trademark Office, it is signed by the Director of the USPTO or an Office official. The patent contains a grant to the patentee, and a printed copy of the specification and drawing is annexed to the patent and forms a part of it. The granted patent confers “the right to exclude others from making, using, offering for sale, or selling the invention throughout the United States or importing the invention into the United States.”  The term of the patent is 20 years from the date on which the application for the patent was filed in the United States or, if the application contains a specific reference to an earlier filed application, from the date of the earliest such application was filed. The patent term is subject to the payment of maintenance fees as provided by law.
 
The exact nature of the right conferred must be carefully distinguished, and the key is in the words “right to exclude” in the phrase just quoted. The patent does not grant the right to make, use, offer for sale or sell or import the invention, but only grants the exclusive nature of the right. Any person is ordinarily free to make, use, offer for sale or sell or import anything he or she pleases, and a grant from the government is not necessary. The patent only grants the right to exclude others from making, using, offering for sale or selling or importing the invention. Since the patent does not grant the right to make, use, offer for sale, or sell, or import the invention, the patentee’s own right to do so is dependent upon the rights of others and whatever general laws might be applicable. A patentee is not authorized to make, use, offer for sale, or sell, or import the invention if doing so would violate any law.
 
An inventor of a new automobile who has obtained a patent thereon would not be entitled to use the patented automobile in violation of the laws of a state requiring a license, nor may a patentee sell an article, the sale of which may be forbidden by a law, merely because a patent has been obtained.

Also a patentee may not make, use, offer for sale, or sell, or import her invention if such action infringes prior patents of others. A patentee may not violate the federal antitrust laws, such as by resale price agreements or entering into combination in restraints of trade, or the pure food and drug laws, by virtue of having a patent. Ordinarily there is nothing that prohibits a patentee from making, using, offering for sale, or selling, or importing his or her own invention, unless he or she thereby infringes another’s patent that is still in force. For example, a patent for an improvement of an original device already patented would be subject to the patent on the device.
 
Maintenance fees must be paid at four-year intervals to maintain the patent in force. After the patent expiration date, it becomes essentially public domain and anyone may make, use, offer for sale, or sell or import the invention without permission of the patentee, provided that matter covered by other unexpired patents is not used. In certain instances, the patent term may be extended for pharmaceuticals and for other circumstances if provided by statute.