copyrighted, the sale of a copperplate under execution did not pass any right to print and publish the map which the copperplate was designed to produce.[1178] A patent right may, however, be subjected, by bill in equity, to payment of a judgment debt of the patentee.[1179] POWER OF CONGRESS OVER PATENT RIGHTS Letters patent for a new invention or discovery in the arts confer upon the patentee an exclusive property in the patented invention which cannot be appropriated or used by the Government without just compensation.[1180] Congress may, however, modify rights under an existing patent, provided vested property rights are not thereby impaired,[1181] but it does not follow that it may authorize an inventor to recall rights which he has granted to others or reinvest in him rights of property which he had previously conveyed for a valuable and fair consideration.[1182] Furthermore, the rights which the present statutes confer are subject to the Anti-Trust Acts, though it can be hardly 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 which are forbidden by those acts exhibit entire consistency in their holdings.[1183] STATE POWER AFFECTING PATENTS AND COPYRIGHTS Nor do the patent laws displace the police or taxing powers of the States. Whatever rights are secured to inventors must be enjoyed in subordination to the general authority of the State over all property within its li