A patent is a grant issued by the federal government that gives an inventor the right to exclude others from making, using, or selling his invention for a specific period of time. The historical purpose of granting these exclusive rights has not changed to this day: it is to encourage public disclosure of new scientific and technological developments that would have a favorable impact upon society and the economy.
The American patent system was largely based on early European concepts. As far back as 1440, English "letters patent" were issued for a method of processing salt. Often, however, such royal grants of monopolies were offered not to encourage invention or business development but to reward court favorites. They generated a great deal of controversy and ultimately led to passage of the Statute of Monopolies (1623), which, by making a patent an exceptional case in which exclusive rights could be granted, restricted the crown's power to confer a monopoly.
The Framers of the Constitution, realizing the importance of stimulating science and technology, authorized Congress to establish and control a patent system. In September 1787 the constitutional convention adopted Article I, section 8: "The Congress shall have Power … To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries."
Congress exercised this power by passing the Patent Act of 1790. The statute placed the burden of granting patents upon a committee made up of the secretary of state, the secretary of war, and the attorney general. Secretary of State thomas jefferson, an early champion of the idea that "ingenuity should receive liberal encouragement," became the first patent examiner.
For several decades there was no requirement that an inventor demonstrate his invention's patentability (its novelty and usefulness) in order to obtain exclusive rights. As a result, a patent was issued almost immediately upon receipt of an application. The process was modified in 1836, when the commissioner of patents was charged with examining every proposal to determine that an invention was both new and useful in concept (though not necessarily that it worked well in practice). These criteria are still applied, together with a requirement that the invention must be "unobvious to one skilled in the art."
Patents are to be distinguished from trademarks and copyrights; generally, the claiming of one does not preclude the claiming of any other, even though they may all apply to a single product. A copyright protects an author's original writing (the tangible expression of an idea). A trademark covers any words used to distinguish one product from another. For example, a computer's interior mechanism and software may be protected by a patent, its instruction manual by a copyright, and its market identification by a trademark. All three legal protections are now considered part of a larger jurisprudential framework called "intellectual property."
A patent may be obtained by anyone who invents or discovers a new, useful, and "unobvious" device or process. If a patent is granted, the inventor gains exclusive rights for a period of seventeen years (fourteen years for the developer of a new design). Any unauthorized manufacture, use, or sale of a patented device or design (or their equivalents) constitutes an infringement.
Patent cases begin at the district court level, may be appealed to the united states court of appeals for the federal circuit, and can be reviewed by the Supreme Court. In Graham v. John Deere Co. of Kansas City (1968) the Court defined the three statutory conditions of patentability: novelty, usefulness, and nonobviousness. The classic modern doctrine of "equivalents" was described in Graver Tank & Manufacturing Co. v. Linde Air Products Co. (1950). One of the largest recent infringement cases was Polaroid Corp. v. Eastman Kodak Co. (1989).
Chisum, Donald S. 1978 Patents: A Treatise on the Law of Patentability, Validity and Infringement. New York: Matthew Bender.
Deller, Anthony W. 1964 Walker on Patents. New York: Lawyers Co-operative.
Lasson, Kenneth 1986 Mousetraps and Muffling Cups: One Hundred Brilliant and Bizarre United States Patents. New York: Arbor House.