is one of limitations, not only upon the powers originally
possessed by the parties thereto, but also upon those conferred on the
Government and every department thereof. It will be freely conceded that
by the principles of our system all power is vested in the people, but
to be exercised in the mode and subject to the checks which the people
themselves have prescribed. These checks are undoubtedly only different
modifications of the same great popular principle which lies at the
foundation of the whole, but are not on that account to be less regarded
or less obligatory.

Upon the power of Congress, the veto of the Executive and the authority
of the judiciary, which is to extend to all cases in law and equity
arising under the Constitution and laws of the United States made in
pursuance thereof, are the obvious checks, and the sound action of
public opinion, with the ultimate power of amendment, are the salutary
and only limitation upon the powers of the whole.

However it may be alleged that a violation of the compact by the
measures of the Government can affect the obligations of the parties, it
can not even be pretended that such violation can be predicated of those
measures until all the constitutional remedies shall have been fully
tried. If the Federal Government exercise powers not warranted by the
Constitution, and immediately affecting individuals, it will scarcely be
denied that the proper remedy is a recourse to the judiciary. Such
undoubtedly is the remedy for those who deem the acts of Congress laying
duties and imposts, and providing for their collection, to be
unconstitutional. The whole operation of such laws is upon the
individuals importing the merchandise. A State is absolutely prohibited
from laying imposts or duties on imports or exports without the consent
of Congress, and can not become a party under these laws without
importing in her own name or wrongfully interposing her authority
against them. By thus interposing, however, she can not rightfully
obstruct the operation of the laws upon individuals. For their
disobedience to or violation of the laws the ordinary remedies through
the judicial tribunals would remain. And in a case where an individual
should be prosecuted for any offense against the laws, he could not set
up in justification of his act a law of the State, which, being
unconstitutional, would therefore be regarded as null and void. The law
of a State can not authorize the commissi