Article 1, Section 9 of the Constitution is a list of eight things Congress is forbidden from doing. Where Section 8 hands Congress its powers, Section 9 draws hard lines around them. The clauses protect individual liberty, block the federal government from playing favorites among states, keep spending under legislative control, and guard against foreign influence on federal officials.
The Eight Clauses at a Glance
Section 9 covers, in order: a now-expired limit on regulating the importation of enslaved people; protection of the writ of habeas corpus; a ban on bills of attainder and ex post facto laws; an apportionment rule for direct taxes; a prohibition on taxing exports; a ban on giving one state’s ports preference over another’s; the requirement that all federal spending flow from an appropriation passed by Congress; and a ban on titles of nobility together with restrictions on gifts from foreign governments.
Clause 1: The Migration or Importation Clause
The first clause was a compromise struck at the Constitutional Convention. It barred Congress from prohibiting the importation of enslaved people until 1808, a 20-year window measured from ratification in 1788, while allowing a tax of up to ten dollars per person imported.1Cornell Law Institute. Article I, Section 9, Clause 1 – Restrictions on the Slave Trade Congress banned the practice effective January 1, 1808, the earliest date the Constitution allowed. The clause has no operative force today.
Clause 2: The Suspension Clause and Habeas Corpus
Habeas corpus lets anyone held in government custody go before a judge and demand a legal justification for the detention. Section 9 forbids the federal government from suspending this right except “when in Cases of Rebellion or Invasion the public Safety may require it.” The Supreme Court has held that this clause limits only the federal government, not the states.2Cornell Law School. Writ of Habeas Corpus and the Suspension Clause
Because the clause sits inside Article 1, which defines congressional powers, most legal scholars and courts read it as giving the suspension power to Congress rather than the President. The writ has been suspended only four times in American history: during the Civil War, in nine South Carolina counties under the Ku Klux Klan Act of 1871, in two provinces of the Philippines in 1905, and in Hawaii after the attack on Pearl Harbor. Each suspension was tied to armed conflict or organized violence, matching the “rebellion or invasion” trigger the Constitution names.
Clause 3: Bills of Attainder and Ex Post Facto Laws
Clause 3 bars Congress from passing bills of attainder or ex post facto laws. Both prohibitions stop Congress from doing what only courts should do.3Legal Information Institute. U.S. Constitution Annotated – Article I, Section 9, Clause 3 – Bills of Attainder
Bills of Attainder
A bill of attainder is a law that singles out a specific person or identifiable group for punishment without a trial. The Supreme Court reads the ban broadly, covering not just criminal penalties like imprisonment but also other forms of punishment such as stripping someone of civil or political rights.4Legal Information Institute. U.S. Constitution Annotated Article I Section 9 Clause 3 Bills of Attainder Doctrine Courts ask three questions: does the law target specific individuals or an easily identifiable group, does it impose punishment, and does it do so without the protections of a judicial proceeding. All three yeses make the law unconstitutional. In Nixon v. Administrator of General Services, the Court applied this framework to a law directed at a former president’s records and upheld it after finding a legitimate nonpunitive purpose.5Cornell Law School – Legal Information Institute. Richard M. Nixon, Appellant, v. Administrator of General Services et al.
Ex Post Facto Laws
An ex post facto law changes the legal consequences of actions after the fact. The Supreme Court identified the core categories early: laws that criminalize conduct that was legal when performed, laws that increase the punishment after the crime was committed, laws that change the rules of evidence to make conviction easier, and laws that aggravate the nature of an offense retroactively. The point is fair notice: people should know what is illegal, and what the penalty is, before they act.
The ex post facto ban applies only to criminal laws. Congress can pass retroactive civil laws, such as tax or regulatory changes, without violating this clause, though other constitutional provisions may still constrain that power.
Clause 4: The Apportionment Rule for Direct Taxes
Clause 4 requires that any “capitation, or other direct, tax” be apportioned among the states based on population as determined by the census.6Legal Information Institute. Direct Taxes and the Sixteenth Amendment In practice, each state’s share of a direct tax would have to match its share of the population, which makes most direct taxes impractical to design. The Supreme Court has explained that “direct taxes” include capitation taxes (a flat per-person charge), taxes on real estate, and taxes on personal property.
This rule collided with the federal income tax in 1895, when the Court in Pollock v. Farmers’ Loan & Trust Co. ruled that a tax on income from property was a direct tax requiring apportionment, effectively striking the income tax down.7Legal Information Institute. Pollock v. Farmers Loan and Trust Co. et al. The states ratified the Sixteenth Amendment in 1913, giving Congress the power to tax incomes “without apportionment among the several States, and without regard to any census or enumeration.”8Library of Congress. U.S. Constitution – Sixteenth Amendment The apportionment rule still governs other direct taxes; the Sixteenth Amendment carved out income.
Clause 5: No Taxes on Exports
Congress is categorically barred from taxing goods exported from any state.9Legal Information Institute. Article I, Section 9, Clause 5 – Prohibition on Taxes on Exports The ban targets charges imposed because goods are being exported. A general property tax that happens to reach export-bound goods does not violate the clause, and legitimate user fees are also permitted. In United States v. United States Shoe Corp., the Supreme Court struck down the Harbor Maintenance Tax because it was calculated on the value of exported cargo rather than the cost of services provided. A valid user fee, the Court said, must be “a charge designed as compensation for government-supplied services, facilities, or benefits” and must “fairly match the exporters’ use of port services and facilities.”10Legal Information Institute. United States v. United States Shoe Corp.
Clause 6: No Preference for the Ports of One State
Clause 6 prohibits federal regulations that give the ports of one state an advantage over the ports of another. Ships traveling between states cannot be forced to dock, clear customs, or pay duties in a state they are not bound for.11Cornell Law School. Prohibition on Port Preferences The clause was written to keep the federal government from steering commerce toward politically favored states. It does not bar every law that ends up helping one port; Congress can legislate under its commerce power even if a particular port benefits, so long as the preference is incidental rather than deliberate.12Constitution Annotated | Congress.gov | Library of Congress. No-Preference Clause for Ports
Clause 7: The Appropriations Clause
Clause 7 is the “power of the purse.” No money can be paid out of the federal Treasury unless Congress has passed a law authorizing the expenditure.13Legal Information Institute. Appropriations Clause The clause also requires the government to publish regular accounts of money received and spent, so the public can track how tax dollars are used.14Cornell Law School. Overview of the Appropriations Clause Congress backs the rule with the Antideficiency Act, which bars federal agencies from spending beyond appropriated amounts and exposes officials who willfully violate it to administrative and even criminal penalties.15U.S. Government Accountability Office. Antideficiency Act
Clause 8: Titles of Nobility and Foreign Emoluments
The last clause of Section 9 has two parts, both aimed at keeping the government democratic in character and free of foreign influence.16Legal Information Institute. Article I, Section 9, Clause 8 – Titles of Nobility and Foreign Emoluments
Titles of Nobility
The United States cannot grant any title of nobility. No federal official can be made a king, duke, or any equivalent. Government authority is meant to come from law and elections, not from hereditary rank.
The Foreign Emoluments Clause
Anyone holding a federal “office of profit or trust” is barred from accepting any gift, payment, office, or title from a foreign government without the express consent of Congress. The phrase is widely agreed to cover all appointed federal officials. Whether it also covers elected officials, including the President, has been debated since the founding. Alexander Hamilton, as Treasury Secretary, produced a list of covered offices for the Senate that included no elected positions; the Department of Justice’s Office of Legal Counsel has since opined that the President holds an “office of profit and trust.”17Constitution Annotated | Congress.gov | Library of Congress. Foreign Emoluments Clause Generally
Congress implements the clause through the Foreign Gifts and Decorations Act, which bars covered federal employees, including the President, Vice President, and Members of Congress, from accepting any gift of more than minimal value from a foreign government without approval. The General Services Administration sets the “minimal value” threshold, which stands at $525 as of 2026.18U.S. General Services Administration. Foreign Gifts
The Foreign Emoluments Clause in Section 9 should not be confused with the separate Domestic Emoluments Clause in Article 2, Section 1, which applies only to the President and bars additional payments from federal or state governments beyond the presidential salary. That clause is absolute; Congress cannot consent to a waiver.19Library of Congress. Emoluments Clause and Presidential Compensation
What Section 9 Does Not Cover
Section 9 restricts the federal government. Restrictions on the states sit in Article 1, Section 10, which independently forbids states from passing bills of attainder, ex post facto laws, or granting titles of nobility.20Legal Information Institute. State Ex Post Facto Laws If your question is about what a state legislature can or cannot do, Section 10 is the clause to read; Section 9 will not answer it. Together the two sections form a two-sided limit that predates the Bill of Rights and represents the framers’ earliest effort to write individual protections directly into the structure of government.