Can Congress Do That, Ten Questions About Federal Power Answered

Ask a member of Congress which clause of the Constitution authorizes a bill, and you will often get the same look you would get asking a restaurant which farm the parsley came from. Polite confusion. A suggestion that the question is beside the point. Possibly a reference to "the general welfare," delivered with the confidence of someone who has never read the sentence it comes from.

The question is not beside the point. It is the point. The federal government is one of enumerated powers. Every federal law must rest on a power the Constitution grants. So the fastest way to test any bill is to ask: which listed power? Here are ten questions citizens ask about Congress, answered with the text and the cases.

The rule behind every answer

Start with the premise, because everything follows from it.

1. Congress has only the powers granted. Article I begins: "All legislative Powers herein granted shall be vested in a Congress of the United States." Herein granted. Not all legislative powers that exist, only those granted in the document.
2. The grants are listed. Article I, Section 8 contains the main list: taxing and spending, borrowing, regulating commerce among the states, naturalization, coining money, post offices, patents, courts, war, armies and navies, the militia, the federal district. Other grants appear elsewhere, such as the enforcement clauses of the 13th, 14th and 15th Amendments.
3. The Necessary and Proper Clause carries the listed powers into execution. It is a means to the listed ends, not a new end of its own. See The Necessary and Proper Clause Was Never Meant to Be a Blank Check.
4. Everything else stays with the states or the people. The Tenth Amendment: "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."

Madison put it in Federalist 45: "The powers delegated by the proposed Constitution to the federal government, are few and defined. Those which are to remain in the State governments are numerous and indefinite." We read that paper closely in Few and Defined, the Promise About Federal Power in Madison's Federalist 45.

Now the questions.

Mandates and taxes

1. Can Congress make you buy a product?

Not under the Commerce Clause. In National Federation of Independent Business v. Sebelius (2012), the Affordable Care Act required most Americans to obtain health insurance or pay a "shared responsibility payment." The government argued that the requirement regulated interstate commerce. Chief Justice Roberts, writing for himself, and four dissenting justices agreed that the Commerce Clause power to regulate commerce does not include a power to compel people to enter commerce. The power to regulate an activity presupposes the activity. If Congress could order you to buy insurance because your not buying it affects the market, it could order you to buy anything, from vegetables to cars, on the same theory.

2. Then how did the mandate survive?

As a tax. Roberts held that the payment could reasonably be read as a tax on not having insurance, collected by the IRS with the ordinary income tax, and that Congress's taxing power supported it. Four justices joined that part of the opinion. The practical lesson is uncomfortable: a mandate that fails as a command may survive as a tax if the penalty is modest and collected like a tax. The political lesson is better: Congress then has to own it as a tax before the voters. Congress later reduced the payment to zero in the tax law enacted in 2017, effective in 2019. We cover the reasoning in John Roberts Called the Mandate a Tax, and Conservatives Still Argue About Why.

Money and the states

3. Can Congress attach conditions to federal grants?

Yes, within limits. In South Dakota v. Dole (1987), Congress had directed the secretary of transportation to withhold 5 percent of certain federal highway funds from any state that allowed people under 21 to buy alcohol. Congress could not set a national drinking age directly. Could it buy one?

The Court, in an opinion by Chief Justice Rehnquist, said yes, 7-2, and set out the limits on conditional spending:

1. The spending must serve the general welfare.
2. The condition must be stated unambiguously, so states know what they are accepting.
3. The condition must be related to the federal interest in the program; highway money and highway safety qualified.
4. The condition must not require the state to do something otherwise unconstitutional.
5. The financial inducement must not be so coercive that "pressure turns into compulsion."

Five percent of highway funds, the Court said, was relatively mild encouragement. Justices Brennan and O'Connor dissented, O'Connor arguing that the drinking age had too little to do with highway spending.

4. Is there a limit on how hard Congress can squeeze?

Yes, and NFIB drew it. The Affordable Care Act expanded Medicaid and told states that if they refused the expansion, they could lose not just the new funds but all of their existing Medicaid money. Seven justices agreed that this crossed the line from encouragement to coercion. Roberts called the threat "a gun to the head." The remedy was to let states decline the expansion without losing their existing funds.

Compare the two cases with some arithmetic. In Dole, the penalty was 5 percent of one category of highway funds, a small share of any state's budget. In NFIB, the Court noted that Medicaid spending accounted for over 20 percent of the average state's total budget. When the penalty is a slice of a highway grant, a state has a real choice. When it is the largest federal grant program to the states, it does not. For the broader argument about strings attached to federal money, see Block Grants or Categorical Grants, and Why the Strings Matter Most.

5. Can Congress order state officers to enforce federal law?

No. This is the anticommandeering rule, and it is one of the strongest protections of federalism the Court has recognized.

• In New York v. United States (1992), the Court struck down a provision requiring states either to regulate low-level radioactive waste as Congress directed or to take title to it. Congress may regulate individuals directly; it may not order state legislatures to legislate.
• In Printz v. United States (1997), it struck down the provision of the Brady Act requiring local sheriffs to run background checks on handgun buyers. Justice Scalia wrote that Congress may not conscript state officers to administer a federal program. See Printz v. United States and the sheriffs who refused to be drafted by Washington.
• In Murphy v. NCAA (2018), it struck down a federal law forbidding states to authorize sports gambling. Telling a state legislature what it may not pass is commandeering just as much as telling it what it must pass.

The rule cuts across political lines. It protects states that decline to help enforce federal gun laws and states that decline to help enforce federal immigration laws. That consistency is a feature. A principle that protects only your side is not a principle.

Commerce and the police power

6. Does Congress have a general police power?

No. The police power, the general authority to legislate for the health, safety, morals and welfare of the people, belongs to the states. Congress has no such grant.

The Court enforced that line in United States v. Lopez (1995). The Gun-Free School Zones Act of 1990 made it a federal crime to possess a gun near a school. The government argued that guns near schools harm education, which harms the economy, which affects interstate commerce. Chief Justice Rehnquist, for a 5-4 majority, held that this chain of inferences would leave no limit on federal power at all, and that possessing a gun near a school is not economic activity. Five years later, in United States v. Morrison (2000), the Court struck down the civil remedy of the Violence Against Women Act on the same reasoning. Gender-motivated violence is a grave crime, and states punish it. That does not make it interstate commerce. See United States v. Lopez Was the First Commerce Clause Limit Since the New Deal.

7. Can Congress regulate purely local activity?

Here the cases are much less friendly. In Wickard v. Filburn (1942), an Ohio farmer grew wheat beyond his federal quota, for use on his own farm. The Court held that Congress could regulate it, because if many farmers did the same, the total effect on the national wheat market would be substantial. In Gonzales v. Raich (2005), the Court applied the same reasoning to marijuana grown at home for personal medical use under California law. Justice Thomas dissented, arguing that a plant that never crossed a state line and was never sold is not commerce among the several states.

Lopez and Raich can coexist only through a distinction: Congress may regulate local economic activity that, in the aggregate, substantially affects interstate commerce, especially as part of a broader regulatory scheme, but may not regulate noneconomic activity on that theory. Thomas is right that "commerce among the several States" meant trade crossing state lines, as we show in What Commerce Among the Several States Meant to the Men Who Wrote It. A wheat field that feeds one farmer's chickens is not that.

Delegation, spending and treaties

8. Can Congress hand its lawmaking power to agencies?

In principle, no. Article I vests "All legislative Powers herein granted" in Congress, and a power vested in one body cannot be given away. In practice, the Court has allowed delegation as long as Congress supplies an "intelligible principle" to guide the agency, a test from J.W. Hampton, Jr. & Co. v. United States (1928). The Court has struck down a statute for excessive delegation only twice, both in 1935: Panama Refining Co. v. Ryan and A.L.A. Schechter Poultry Corp. v. United States.

The tide is turning. In Gundy v. United States (2019), Justice Gorsuch, joined by Chief Justice Roberts and Justice Thomas, wrote a dissent calling for a return to the original rule. In West Virginia v. EPA (2022), the Court held that agencies need clear congressional authorization to decide questions of vast economic and political significance. And in Loper Bright Enterprises v. Raimondo (2024), it overruled Chevron, ending automatic deference to agency readings of ambiguous statutes. For the run of cases, see Five Times the Court Told an Agency That Big Questions Belong to Congress.

9. Can Congress spend money on anything it likes?

This is the oldest argument in American constitutional law. Article I, Section 8 gives Congress power to "lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States." Madison read "general Welfare" as a summary of the powers that follow: Congress may spend to carry out its listed powers. Hamilton read it as an independent power to spend for any purpose that serves the general welfare of the nation, as opposed to a local one.

In United States v. Butler (1936), the Court sided with Hamilton on the spending question, while striking down the farm program before it on other grounds. Ever since, the spending power has been the broadest in Congress's arsenal. Even on Hamilton's view, though, the welfare must be general, national rather than local, and spending conditions remain bound by Dole and NFIB. The full argument is in Madison and Hamilton Fought Over Two Words, General Welfare, and We Still Pay.

10. Can a treaty give Congress powers it would not otherwise have?

In Missouri v. Holland (1920), the Court upheld a federal law protecting migratory birds, enacted to carry out a treaty with Great Britain, even though a lower court had struck down a similar statute without a treaty. Justice Holmes suggested that the treaty power could support legislation Congress could not otherwise pass. That idea is dangerous: it would let the president and two-thirds of the Senate expand federal power by signing a treaty with any willing foreign government. In Bond v. United States (2014), the Court avoided the constitutional question by reading a chemical weapons statute narrowly, so that it did not reach a purely local assault. Justices Scalia, Thomas and Alito would have gone further and limited the treaty power itself. The safe answer is that a treaty cannot enlarge the Constitution, and conservatives should insist on it.

The strongest objection, answered

The best case for broad federal power goes like this. The economy is national. Problems cross state lines. The Founders wrote for an agricultural nation of four million people. A modern country of over three hundred million needs a national government able to address national problems, and the Court has rightly recognized that since 1937.

Answer it in four steps.

1. The Constitution provides a way to add powers. Article V. If a national problem requires a new federal power, the people can grant it, as they did with the income tax in the 16th Amendment.
2. Many listed powers are already broad. Commerce, taxing and spending reach a great deal. The question is not whether Washington can act on national problems, but whether there is any limit at all.
3. A government with no limits cannot be held accountable. When every level does everything, no one is responsible for anything.
4. The states are not obstacles; they are the design. Federalism lets fifty governments try different answers and lets citizens choose among them.

The case in brief

1. Congress has only the powers "herein granted," so every bill must answer the question: which listed power?
2. NFIB v. Sebelius (2012) held that the commerce power cannot compel purchases, though the mandate survived as a tax, and that threatening all existing Medicaid funds was coercive.
3. Conditions on grants are allowed within the limits of South Dakota v. Dole (1987), and Congress may never commandeer state legislatures or officers under New York, Printz and Murphy.
4. There is no federal police power under Lopez and Morrison, though Wickard and Raich still let Congress reach local economic activity in the aggregate.
5. The delegation, spending and treaty powers have limits worth defending, and Article V is the honest way to add powers.

What you can do: pick one bill your representative has sponsored, check its text on Congress.gov for a stated source of constitutional authority, and ask the office which listed power it relies on. You can find the office on the My Representatives page.