The object of these most important provisions in the national constitution has often been discussed, both here and elsewhere. It is exhibited with great clearness and force by one of the distinguished persons who framed that instrument. "Bills of attainder, _ex post facto_ laws, and laws impairing the obligation of contracts, are contrary to the first principles of the social compact, and to every principle of sound legislation. The two former are expressly prohibited by the declarations prefixed to some of the State constitutions, and all of them are prohibited by the spirit and scope of these fundamental charters. Our own experience has taught us, nevertheless, that additional fences against these dangers ought not to be omitted. Very properly, therefore, have the convention added this constitutional bulwark, in favor of personal security and private rights; and I am much deceived, if they have not, in so doing, as faithfully consulted the genuine sentiments as the undoubted interests of their constituents. The sober people of America are weary of the fluctuating policy which has directed the public councils. They have seen with regret, and with indignation, that sudden changes, and legislative interferences in cases affecting personal rights, become jobs in the hands of enterprising and influential speculators, and snares to the more industrious and less informed part of the community. They have seen, too, that one legislative interference is but the link of a long chain of repetitions; every subsequent interference being naturally produced by the effects of the preceding."