e latter can be protected, if at all, only by letters
patent.[1177] Since copyright is a species of property distinct from the
ownership of the equipment used in making copies of the matter
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 limits. A statute of Kentucky requiring the condemnation of
illuminating oils which were inflammable at less than 130 degrees
Fahrenheit, was held not to interfere with any right secured by the
patent laws, although the oil for which the patent was issued could not
be made to comply with State specifications.[1184] In the absence of
federal legislation, a State may prescribe reasonable regulations for
the transfer of patent rights so as to protect its citizens from fraud.
Hence a requirement of State law that the words "given for a patent
right" appear on the face of notes given in payment for such right is
not unconstitutional.[1185] Royalties received from patents or
copyrights are subject to a nondiscriminating State income tax, a
holding to the con