"They appertain rather to the execution of an important trust invested by the Constitution, and to the obligation to fulfill that trust on the part of the government, namely, the trust and the duty of creating and maintaining a uniform and pure metallic standard of value throughout the Union.
The power to coining money and of regulating its value was delegated to Congress by the Constitution for the very purpose, as assigned by the framers of that instrument, of creating and preserving the uniformity and purity of such a standard of value; and on account of the impossibility which was foreseen of otherwise preventing the inequalities and the confusion necessarily incident to different views of policy, which in different communities would be brought to bear on this subject. The power to coin money being thus given to Congress, founded on public necessity, it must carry with it the correlative power of protecting the creature and object of that power. It cannot be imputed to wise and practical statesmen, nor is it consistent with common sense, that they should have vested this high and exclusive authority, and with a view to objects partaking of the magnitude of the authority itself, only to be rendered immediately vain and useless, as must have been the case had the government been left disabled and impotent as to the only means of securing the objects in contemplation.
"If the medium which the government was authorized to create and establish could immediately be expelled, and substituted by one it had neither created, estimated, nor authorized, - one possessing no intrinsic value, - then the power conferred by the Constitution would be useless, - wholly fruitless of every end it was designed to accomplish.
Whatever functions Congress are, by the Constitution, authorized to perform, they are, when the public good requires it, bound to perform; and on this principle, having emitted a circulating medium, a standard of value 568*568 indispensable for the purposes of the community, and for the action of the government itself, they are accordingly authorized and bound in duty to prevent its debasement and expulsion, and the destruction of the general confidence and convenience, by the influx and substitution of a spurious coin in lieu of the constitutional currency."