The fact that states are prohibited from impairing contracts while no such provision is imposed on the federal government is significant when there is occasion to consider the validity of state statutes as to discharge in bankruptcy or payment in legal tender currency. It is a common provision in laws relating to bankruptcy that after the application of all his property to the payment of his debts the bankrupt is discharged from further liability (see above, § 101), but a state bankruptcy statute with these provisions could not be made applicable to debts already created by contract, for to do so would be to deprive the creditor of legal redress for the violation of such contract by one who should subsequently be declared a bankrupt and discharged (Sturges v. Crowninshield and Ogden v. Saunders). There is no such limitation on the federal government, and as Congress is expressly given authority to pass general laws on the subject of bankruptcy (Art. I, § 8, ¶ 4) a discharge under a federal bankruptcy law will relieve the bankrupt from further liability on debts created prior to the passage of such a statute as well as on those contracted subsequently. For similar reasons, although a state may perhaps declare what currency shall be receivable as a legal tender in the absence of any federal statute on the subject, it cannot provide for the extinguishment of indebtedness by payment in some form of money not recognized by the law of the state as a legal tender when the contract was made; but Congress may pass legal tender statutes applicable to debts already contracted as well as those subsequently contracted (Legal Tender Case).