The full text of the 10th Amendment reads: “The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.”1Congress.gov. Tenth Amendment Ratified on December 15, 1791, as the closing provision of the Bill of Rights, that single sentence draws the boundary between federal and state authority: the federal government has the powers the Constitution gives it, the states are blocked from a few specific things, and everything else belongs to state governments or to citizens themselves.2National Archives. Bill of Rights (1791)
The Exact Words
“The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.”
The sentence has three moving parts. Powers the Constitution hands to the federal government. Powers the Constitution blocks the states from exercising. Everything left over. That leftover category is what the amendment “reserves,” and it goes to the states or to the people.
The amendment does not grant any new power. It confirms an arrangement the rest of the Constitution already sets up.
What Each Part Means
“Powers delegated to the United States” refers mainly to the enumerated powers listed in Article I, Section 8, along with authorities scattered elsewhere in the document. The Article I list includes taxing, borrowing money, regulating commerce among the states, coining money, establishing post offices, declaring war, and raising an army and navy.3Congress.gov. Article I Section 8 – Enumerated Powers Other federal powers appear in Article II (treaties, for example) and in later amendments.
“Prohibited by it to the States” points to the specific limits the Constitution places on state governments, such as the bans in Article I, Section 10 on states coining their own money or entering into treaties. States cannot exercise those powers even though the federal government can.
“Reserved to the States respectively, or to the people” is the residual clause. Any authority the Constitution neither grants to the federal government nor forbids to the states stays with the states or with individual citizens. That is where the bulk of American law actually lives.
The Missing Word: “Expressly”
The most consequential word in the 10th Amendment is one that was deliberately left out. The Articles of Confederation, the country’s first governing document, had said each state kept “every Power, Jurisdiction and right, which is not by this confederation expressly delegated to the United States.”4Congress.gov. Amdt10.2 Historical Background on Tenth Amendment That word had crippled the national government, limiting it to authorities spelled out in exact terms.
When Congress drafted the 10th Amendment, both chambers voted down proposals to insert “expressly” before “delegated.”4Congress.gov. Amdt10.2 Historical Background on Tenth Amendment The drafters had lived through the failure of the Articles and refused to repeat it. Chief Justice John Marshall later explained in McCulloch v. Maryland (1819) that the framers “had experienced the embarrassments resulting from the insertion of this word in the Articles of Confederation, and probably omitted it to avoid those embarrassments.”5Justia. McCulloch v. Maryland, 17 U.S. 316 (1819)
Because the amendment says “not delegated” instead of “not expressly delegated,” Congress can pass laws that go beyond the literal checklist of enumerated powers, as long as those laws carry out a power the Constitution does grant. The Necessary and Proper Clause in Article I, Section 8 backs that up, giving Congress authority to “make all Laws which shall be necessary and proper for carrying into Execution” its other powers.6Congress.gov. Article I Section 8 Clause 18
The Supreme Court has read the amendment in that same spirit. In United States v. Darby (1941), it called the 10th Amendment “but a truism that all is retained which has not been surrendered,” finding nothing in its history to suggest it was ever meant to do more than restate the federal-state relationship the Constitution already created.7Library of Congress. United States v. Darby, 312 U.S. 100 (1941)
That does not make the text toothless. When Congress reaches past its enumerated powers, the amendment marks the line it crossed. In United States v. Lopez (1995), the Court struck down the Gun-Free School Zones Act, holding the law “neither regulates a commercial activity nor contains a requirement that the possession be connected in any way to interstate commerce.”8Supreme Court of the United States. United States v. Lopez
What Powers the States Keep
Because the federal government has a defined list of jobs, state governments operate under a much wider general authority to pass laws protecting public health, safety, and welfare. Legal tradition calls this the police power, and it covers most of the law you actually deal with in daily life.
Criminal codes. Public school systems. Professional licensing for doctors and lawyers. Marriage and divorce. Zoning. Property taxes. Driver’s licenses. The Constitution says nothing about who can practice medicine or how a local school district runs, so each state decides for itself.
States also draw emergency authority from this same reservoir. During public health crises, governors can declare emergencies that activate broader executive powers, including isolation and quarantine orders, temporary changes to professional licensing requirements, and reallocation of state funds. That authority traces directly back to the 10th Amendment’s reservation of police power to the states.
What It Means When Federal and State Law Clash
Reserving powers to the states does not make state law supreme. Article VI of the Constitution, the Supremacy Clause, declares that the Constitution and valid federal laws “shall be the supreme Law of the Land.”9Congress.gov. Article VI Clause 2 – Supreme Law When a state law genuinely conflicts with a valid federal law, federal law wins. The word doing the work there is “valid”: a federal law that exceeds Congress’s enumerated powers is not a valid exercise of federal authority in the first place.
Federal Money With Strings Attached
Congress often works around the reserved-powers problem by conditioning federal grants. Under South Dakota v. Dole (1987), Congress can attach conditions to money it sends to states, provided the spending serves the general welfare, the conditions are clearly stated, they relate to the program being funded, and they do not require states to violate the Constitution.10Justia. South Dakota v. Dole, 483 U.S. 203 (1987) That case upheld withholding a portion of highway funds from states that set their drinking age below 21.
The Anti-Commandeering Rule
What Congress cannot do is order state governments to run federal programs. In New York v. United States (1992), the Court struck down a law that required states either to regulate radioactive waste on federal terms or take title to it. Congress could not “commandeer state regulatory processes by ordering states to enact or administer a federal regulatory program.”11Congress.gov. Amdt10.4.2 Anti-Commandeering Doctrine
Printz v. United States (1997) extended the rule to state executive officers, striking down the Brady Handgun Violence Prevention Act’s requirement that local sheriffs conduct background checks on gun buyers.12Supreme Court of the United States. Printz v. United States And Murphy v. NCAA (2018) invalidated the federal ban on states authorizing sports betting, holding that Congress cannot “unequivocally dictate what a state legislature may and may not do.”13Supreme Court of the United States. Murphy v. National Collegiate Athletic Assn. (2018)
The practical rule is that the federal government can regulate you directly and can offer states money to encourage cooperation, but it cannot draft state legislatures or state officers into federal service.
Reserved to the People
The last three words of the amendment do work of their own. Authority not delegated to the federal government and not exercised by the states stays with the people. The clause treats citizens as the original source of governmental power: what they did not hand upward, they kept.
The Ninth Amendment sits next to this idea but addresses something different. It says, “The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.”14Congress.gov. Ninth Amendment The Ninth Amendment is about individual rights the Constitution does not list. The 10th Amendment is about governmental powers the Constitution does not grant. One protects freedoms; the other limits authority.
Courts have done less with the “to the people” language than with the state-power side of the sentence. Most 10th Amendment litigation involves states pushing back against Washington, not individuals invoking the clause on their own behalf. Even so, the phrase carries a structural point that the rest of the text depends on: government power flows upward from citizens, not downward from the state.