Article I, Section 8, Clause 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.
Letters patent for a new invention or discovery in the arts confer upon the patentee an exclusive property in the patented invention that cannot be appropriated or used by the government without just compensation.1 Congress may, however, modify rights under an existing patent, provided vested property rights are not thereby impaired,2 but it does not follow that it may authorize an inventor to recall rights that he has granted to others or reinvest in him rights of property that he had previously conveyed for a valuable and fair consideration.3 Furthermore, the rights the present statutes confer are subject to the antitrust laws, though it can hardly be said that the cases in which the Court has endeavored to draw the line between the rights claimable by patentees and the kind of monopolistic privileges that are forbidden by those acts are entirely consistent in their holdings.4
Congress has the power to pass copyright laws that, in its political judgment, will serve the ends of the Copyright Clause. Congress may
promote the Progress of Science (i.e., the creation and dissemination of knowledge and learning) not only by providing incentives for new works, but also by conferring copyright protection to works in the public domain.5The Copyright Clause also broadly empowers Congress to extend the terms of existing copyrights, so long as the extended terms are for determinable periods.6