The Constitution always accompanies the law, and the latter can have no force which the former does not allow to it.  If the reasoning were thrown into the form of special pleading, it would stand thus:  the plaintiff declares on his debt; the defendant pleads his discharge under the law; the plaintiff alleges the law unconstitutional; but the defendant says, You knew of its existence; to which the answer is obvious and irresistible, I knew its existence on the statute-book of New York, but I knew, at the same time, it was null and void under the Constitution of the United States.

The language of another leading decision is, “A law in force at the time of making the contract does not violate that contract”; but the very question is, whether there be any such law “in force”; for if the States have no authority to pass such laws, then no such law can be in force.  The Constitution is a part of the contract as much as the law, and was as much in the contemplation of the parties.  So that the proposition, if it be admitted that the law is part of the contract, leaves us just where it found us:  that is to say, under the necessity of comparing the law with the Constitution, and of deciding by such comparison whether it be valid or invalid.  If the law be unconstitutional, it is void, and no party can be supposed to have had reference to a void law.  If it be constitutional, no reference to it need be supposed.

2.  But the proposition itself cannot be maintained.  The law is no part of the contract.  What part is it? the promise? the consideration? the condition?  Clearly, it is neither of these.  It is no term of the contract.  It acts upon the contract only when it is broken, or to discharge the party from its obligation after it is broken.  The municipal law is the force of society employed to compel the performance of contracts.  In every judgment in a suit on contract, the damages are given, and the imprisonment of the person or sale of goods awarded, not in performance of the contract, or as part of the contract, but as an indemnity for the breach of the contract.  Even interest, which is a strong case, where it is not expressed in the contract itself, can only be given as damages.  It is all but absurd to say that a man’s goods are sold on a fieri facias, or that he himself goes to jail, in pursuance of his contract.  These are the penalties which the law inflicts for the breach of his contract.  Doubtless, parties, when they enter into contracts, may well consider both what their rights and what their liabilities will be by the law, if such contracts be broken; but this contemplation of consequences which can ensue only when the contract is broken, is no part of the contract itself.  The law has nothing to do with the contract till it be broken; how, then, can it be said to form a part of the contract itself?