Constitution

Article I, Section 10: Limits on the States

Section 10 forbids the states to make treaties, coin money, impair contracts or pass ex post facto laws, and bars state tariffs and compacts without Congress.

4Conservative Editors · Published November 8, 2026

The text

No State shall enter into any Treaty, Alliance, or Confederation; grant Letters of Marque and Reprisal; coin Money; emit Bills of Credit; make any Thing but gold and silver Coin a Tender in Payment of Debts; pass any Bill of Attainder, ex post facto Law, or Law impairing the Obligation of Contracts, or grant any Title of Nobility.

No State shall, without the Consent of the Congress, lay any Imposts or Duties on Imports or Exports, except what may be absolutely necessary for executing it's inspection Laws: and the net Produce of all Duties and Imposts, laid by any State on Imports or Exports, shall be for the Use of the Treasury of the United States; and all such Laws shall be subject to the Revision and Controul of the Congress.

No State shall, without the Consent of Congress, lay any Duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State, or with a foreign Power, or engage in War, unless actually invaded, or in such imminent Danger as will not admit of delay.

In plain English

Section 10 is the mirror of Section 9: it lists things the states may not do. Its prohibitions come in two kinds.

Clause 1: absolute prohibitions. No state may:

  • make treaties, alliances or confederations, or grant letters of marque (licenses for private warships);
  • coin money, issue paper money ("Bills of Credit"), or make anything but gold and silver coin legal tender for debts;
  • pass bills of attainder or ex post facto laws;
  • pass any law "impairing the Obligation of Contracts";
  • grant titles of nobility.

Clause 2: taxes on trade. Without Congress's consent, no state may tax imports or exports, except what is absolutely necessary to pay for inspection laws. Any net proceeds go to the federal Treasury, and Congress may revise such laws.

Clause 3: other consent requirements. Without Congress's consent, no state may levy tonnage duties, keep troops or warships in peacetime, make agreements or compacts with another state or a foreign power, or engage in war unless invaded or in imminent danger.

The section makes the national government the sole voice of the country in foreign affairs, war and money, and it protects certain private rights against state legislatures.

What the Founders said

The Framers had seen what the states did under the Articles of Confederation: printing paper money that collapsed in value, passing debtor-relief laws that cancelled or postponed private debts, and taxing each other's goods. Madison, writing in Federalist No. 44, treated these prohibitions as among the most necessary in the plan. He wrote that "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," and that the people were weary of the "fluctuating policy" that had governed public councils.

On paper money he was blunt: the loss Americans had suffered from it was an accumulation of guilt that could be expiated only by a voluntary sacrifice on the altar of justice. The Contract Clause, in particular, was understood as a guard for creditors and for anyone who relied on a binding agreement.

How the courts have read it

  • Fletcher v. Peck (1810): Georgia could not revoke a land grant once made, even one procured by bribery, because a grant is a contract.
  • Trustees of Dartmouth College v. Woodward (1819): a corporate charter is a contract; New Hampshire could not take over the college by statute.
  • Craig v. Missouri (1830): state-issued loan certificates meant to circulate as money were forbidden "Bills of Credit."
  • Virginia v. Tennessee (1893): only compacts that increase state power at the expense of federal supremacy require Congress's consent.
  • Home Building & Loan Association v. Blaisdell (1934): a Depression-era mortgage moratorium was upheld as a reasonable exercise of the state's police power, a sharp turn away from the clause's original strength.
  • Energy Reserves Group v. Kansas Power & Light (1983): the Court set out the modern test asking whether a law substantially impairs a contract and, if so, whether it serves a significant and legitimate public purpose by reasonable means.
  • Michelin Tire Corp. v. Wages (1976): a nondiscriminatory property tax on imported goods no longer in transit is not an "Impost."

Why it matters now

The Contract Clause was once one of the most litigated provisions in the Constitution and one of the strongest protections for economic liberty. Since Blaisdell it has been weakened almost to the point of a balancing test. Eviction moratoriums, retroactive changes to public pensions and other emergency measures raise the old question again: can a legislature rewrite private bargains because the times are hard? The Framers, who had lived through exactly that, said no.

The bans on state treaties and war are a reminder that federalism has two sides. States keep broad powers over their own affairs, but the Constitution speaks for the nation with one voice abroad. Interstate compacts, now common for rivers, ports and transit, sit between those poles and remain subject to Congress where they touch federal power.

Finally, the gold-and-silver tender clause binds only the states. It shows how seriously the Founders took sound money, a concern that still informs debates over inflation and the Federal Reserve.

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