by Congress. Broadly speaking, the Court has approved
regulations which have a trivial or remote relation to the operation of
the postal service, while disallowing those which constitute a serious
impediment to it. Thus a State statute which granted to one company an
exclusive right to operate a telegraph business in the State was found
to be incompatible with a federal law which, in granting to any
telegraph company the right to construct its lines upon post roads, was
interpreted as a prohibition of State monopolies in a field which
Congress was entitled to regulate in the exercise of its combined power
over commerce and post roads.[1150] An Illinois statute which, as
construed by the State courts, required an interstate mail train to make
a detour of seven miles in order to stop at a designated station, also
was held to be an unconstitutional interference with the power of
Congress under this clause.[1151] But a Minnesota statute which required
intrastate trains to stop at county seats was found to be
unobjectionable.[1152] Local laws classifying postal workers with
railroad employees for the purpose of determining a railroad's liability
for personal injuries,[1153] or subjecting a union of railway mail
clerks to a general law forbidding any "labor organization" to deny any
person membership because of his race, color or creed,[1154] have been
held not to conflict with national legislation or policy in this field.
Despite the interference _pro tanto_ with the performance of a federal
function, a State may arrest a postal employee charged with murder while
he is engaged in carrying out his official duties,[1155] but it cannot
punish a person for operating a mail truck over its highways without
procuring a driver's license from State authorities.[1156]

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.

Copyrights and Patents

SCOPE OF THE POWER

This clause is the foundation upon which the national patent and
copyright laws rest, although it uses neither of those terms. So far as
patents are concerned, modern legislation harks back to the Statute of
Monopolies of 1624, whereby Parliament endowed inventors with the sole
right to their inventions for fourteen years.[1157] Copyright law, in
turn, traces back to the statute of 1710 which secur