U.S. CONST. ART. 1, SECT 10.
The power of changing the relative situation of debtor and creditor, of interfering with contracts, a power which comes home to every man, touches the interest of all, and controls the conduct of every individual in those things which he supposes to be proper for his own exclusive management, had been used to such an excess by the state legislatures, as to break in upon the ordinary intercourse of society, and destroy all confidence between man and man. This mischief had become so great, so alarming, as not only to impair commercial intercourse and threaten the existence of credit, but to sap the morals of the people and destroy the sanctity of private faith. To guard against the continuance of the evil was an object of deep interest with all the truly wise, as well as the virtuous, of this great community, and was one of the important benefits expected from a reform of the government.