AP® United States Government and Politics review sheet from Aim for Five (aimforfive.com/gov/units/1/1-8)
Unit 1 · Topic 1.8
1.8 Constitutional Interpretations of Federalism
The line between national and state power depends on how courts read a few clauses: the Necessary and Proper Clause, the Commerce Clause, the Supremacy Clause and the Fourteenth Amendment. McCulloch v. Maryland (1819) expanded national power, while United States v. Lopez (1995) set a limit on it. Knowing both cases lets you predict how the Court would handle a new federalism dispute.
Key terms
- Necessary and Proper Clause
- Commerce Clause
- Supremacy Clause
- Fourteenth Amendment
- McCulloch v. Maryland
- United States v. Lopez
The four clauses that move the line
- Necessary and Proper Clause (Article I, Section 8, last clause): Congress can make all laws necessary and proper for carrying out its listed powers. Also called the elastic clause because it stretches national power through implied powers.
- Commerce Clause (Article I, Section 8): Congress can regulate commerce with foreign nations, among the states and with Native American tribes. Since the late 1930s the Court has read it broadly, letting Congress regulate many activities that affect the national economy.
- Supremacy Clause (Article VI): the Constitution, federal laws made under it and treaties are the supreme law of the land. When a valid federal law conflicts with a state law, the federal law wins.
- Fourteenth Amendment (1868): its Due Process and Equal Protection Clauses say no state may deny people life, liberty or property without due process, or deny anyone equal protection of the laws. These clauses let federal courts and Congress limit state actions, especially on civil rights and liberties (Unit 3).
McCulloch v. Maryland (1819)
Facts: Congress chartered the Second Bank of the United States in 1816. Maryland passed a tax on banks not chartered by the state, which in practice targeted the national bank's Baltimore branch. James McCulloch, an official at that branch, refused to pay.
Questions: Can Congress create a bank when the Constitution never mentions banks? Can a state tax a federal institution?
Holding: Yes to the first, no to the second. The Court, led by Chief Justice John Marshall, ruled unanimously for the national government.
Reasoning: Creating a bank is a reasonable way to carry out enumerated powers like taxing, borrowing and supporting armies, so the Necessary and Proper Clause allows it. “Necessary” means useful or appropriate, not absolutely essential. As for the tax, Marshall wrote that “the power to tax involves the power to destroy.” Letting a state tax a federal institution would let states undermine national laws, which the Supremacy Clause forbids.
Significance: McCulloch established broad implied powers and national supremacy, making it the foundation for a strong national government.
United States v. Lopez (1995)
Facts: The Gun-Free School Zones Act of 1990 made it a federal crime to have a gun within 1,000 feet of a school. Alfonso Lopez Jr., a high school senior in San Antonio, Texas, brought a handgun to school and was charged under the federal law.
Question: Does the Commerce Clause give Congress power to pass this law?
Holding: No. In a 5–4 decision written by Chief Justice William Rehnquist, the Court struck down the law.
Reasoning: Possessing a gun near a school is not an economic activity, and it doesn't substantially affect interstate commerce. If Congress could regulate it under the Commerce Clause, there would be almost nothing Congress couldn't regulate, erasing the line between national and local power. Schools and local crime are traditionally state matters.
Significance: It was the first time in nearly 60 years that the Court limited Congress's commerce power, and it signaled a shift toward protecting state authority. Five years later, United States v. Morrison (2000) applied the same reasoning to strike down part of the Violence Against Women Act.
Comparing the two cases
| Case | Clause at the center | Who won | Effect on federalism |
|---|---|---|---|
| McCulloch v. Maryland (1819) | Necessary and Proper; Supremacy | National government | Expanded national power |
| United States v. Lopez (1995) | Commerce | The individual and, in effect, state authority | Limited national power |
Worked examples
Try each one yourself first, then open the solution.
- Example 1
SCOTUS comparison: a new commerce case
Congress passes a law making it a federal crime to carry a knife in a public park. A person arrested in a city park argues the law is unconstitutional. Using United States v. Lopez, explain how the Court would likely rule.
Show the solutionHide the solution
- Step 1: Identify the shared fact: like gun possession near a school, carrying a knife in a park is a non-economic activity that is traditionally handled by state and local law.
- Step 2: State the Lopez reasoning: the Commerce Clause doesn't let Congress regulate activity that isn't economic and doesn't substantially affect interstate commerce.
- Step 3: Apply it: the knife law has the same weakness, so it likely exceeds Congress's commerce power.
- Step 4: Explain the federalism effect: striking it down would protect state authority over local criminal law.
Answer: The Court would likely strike down the law, as in Lopez, because carrying a knife in a park isn't economic activity that substantially affects interstate commerce, so the law exceeds Congress's commerce power and intrudes on state police power.
Common mistakes
- Saying Lopez was about the Second Amendment. It was about the Commerce Clause and the limits of Congress's power, not gun rights.
- Saying McCulloch was decided under the Commerce Clause. It turned on the Necessary and Proper Clause and the Supremacy Clause.
- Writing that Lopez ended broad commerce power. It set a limit; Congress still regulates a huge range of economic activity under that clause.
On the exam
- McCulloch and Lopez are required cases. The SCOTUS comparison question may pair either one with an unfamiliar case, so know facts, holding, reasoning and whether national power grew or shrank.
- When a question asks about the Supremacy Clause, think conflicts between valid federal and state law; when it asks about implied powers, think Necessary and Proper and McCulloch.
Connected topics
Videos
Check yourself
5 questions on 1.8 Constitutional Interpretations of Federalism. Pick an answer to see if you got it, and why.
Let the end be legitimate, let it be within the scope of the constitution, and all means which are appropriate, which are plainly adapted to that end, which are not prohibited, but consist with the letter and spirit of the constitution, are constitutional.
… That the power to tax involves the power to destroy; that the power to destroy may defeat and render useless the power to create; that there is a plain repugnance in conferring on one government a power to control the constitutional measures of another, which other, with respect to those very measures, is declared to be supreme over that which exerts the control, are propositions not to be denied.
Chief Justice John Marshall, opinion of the Court, McCulloch v. Maryland, 1819
The first paragraph is an interpretation of which part of the Constitution?
Based on the second paragraph, the Court held that Maryland's tax on the Bank of the United States was
How did the decision in McCulloch v. Maryland differ from the decision in United States v. Lopez (1995)?
Congress passes the Safe Parks Act, which makes it a federal crime to carry a knife longer than four inches within 1,000 feet of a public park. Supporters argue that violence near parks discourages tourism and travel, which in turn hurts the national economy. A man arrested under the law challenges it in federal court.
Hypothetical scenario
Based on the holding in United States v. Lopez (1995), the man's strongest argument is that the law
Which of the following, if added to the law, would most strengthen the government's defense of the Safe Parks Act?
0 of 5 answered