A patent gives a patent owner an exclusive right (a monopoly) in an invention for a limited period of time. There are three kinds of patents; utility, plant, and design. For utility and plant patents filed in the United States on or after June 8, 1995 the term of the patent lasts 20 years from the date the patent application was filed. In some cases the term is measured from the date that a related patent application was filed. The term of a design patent lasts 14 years from the date the patent issues. The design patent gives its owner a 14 year monopoly in the ornamental aspects of the design of an article of manufacture.
United States law awards the exclusive right (monopoly) to the first to invent; however, the term of the utility and plant patent is measured from the filing date of the patent application. Recognition of the first to invent in the United States is different from the European system that recognizes the first to file the patent application and awards the exclusive right accordingly.
The legal authority for a patent is found in article I, section 8, clause 8 of the United States Constitution. The statutory law applicable to patents is found in the Patent Act, Title 35 of the United State Code. An application for a patent is submitted to the United States Patent and Trademark Office (USPTO) for examination. The application is examined to determine whether the claimed invention is novel, non-obvious, and useful, and that the best mode has been disclosed in an enabled application. Whether or not a patent application has met the legal requirements is the subject of correspondence (known as patent prosecution) between the inventor and the PTO. The time between filing the patent application and issuance of the patent grant varies; usually at least 12-18 months in the most expeditious case.