The separation of powers - The powers of Congress

Learning Outcomes

This article explains Congress’s constitutional powers within the separation of powers framework, including:

• Identifying the enumerated and enforcement powers that authorize federal legislation, and using the Necessary and Proper Clause as a supporting, not stand‑alone, source of authority.
• Distinguishing among Congress’s commerce, taxing, spending, war, and post–Civil War Amendment enforcement powers, and matching each doctrine to common MBE fact patterns.
• Evaluating whether a federal statute falls within one of the three modern Commerce Clause categories and whether the regulated activity is economic or non‑economic.
• Applying limits on Congress’s powers, such as the lack of a general federal police power, the Tenth Amendment, and the anti‑commandeering principle, to determine when federal regulation of states is invalid.
• Analyzing conditional spending programs for general‑welfare, clarity, germaneness, and coercion issues.
• Recognizing when Congress may regulate private conduct directly under the Thirteenth Amendment or under valid commerce, taxing, or spending legislation.
• Assessing whether legislation enacted under the Fourteenth and Fifteenth Amendments satisfies the state‑action requirement and the “congruence and proportionality” standard.
• Using the Supremacy Clause and preemption doctrines to decide when valid federal law displaces state law, and distinguishing express, field, and conflict preemption.
• Spotting delegation problems, legislative vetoes, and other structural defects that make a federal statute or administrative scheme unconstitutional on MBE questions.

MBE Syllabus

For the MBE, you are required to understand Congress's constitutional powers and their limits, with a focus on the following syllabus points:

• The idea of a federal government of limited, enumerated powers, and the role of the Necessary and Proper Clause.
• The scope of the Commerce Clause, including channels, instrumentalities, and activities that substantially affect interstate commerce.
• Congress’s taxing and spending power, including the “general welfare” language and conditions on federal funds.
• Congress’s war and defense powers during wartime and peacetime.
• Congress’s enforcement powers under the Thirteenth, Fourteenth, and Fifteenth Amendments.
• Limits on Congress, including the absence of a general police power, the Tenth Amendment and anti-commandeering, state sovereign interests, and delegation to administrative agencies.
• The Supremacy Clause and preemption of state law by valid federal law.

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. Congress enacts a law requiring all states to adopt a uniform system for licensing drivers. Which is the strongest constitutional objection?
   1. Congress lacks authority under the Commerce Clause.
   2. The law violates the Tenth Amendment by commandeering state legislatures.
   3. Congress may regulate for the general welfare.
   4. Congress can preempt all state regulation.
2. Which of the following is a valid exercise of Congress’s spending power?
   1. Congress taxes only out-of-state businesses.
   2. Congress spends to further the general welfare, attaching reasonable conditions to federal grants.
   3. Congress spends to regulate purely local, non-economic activity.
   4. Congress spends to enforce state criminal laws.
3. Congress passes a statute prohibiting racial discrimination by private landlords. Which constitutional provision best supports this law?
   1. The Commerce Clause.
   2. The Tenth Amendment.
   3. The Privileges and Immunities Clause.
   4. The General Welfare Clause.

Introduction

The U.S. Constitution divides governmental power among three branches. Congress, as the legislative branch, is not a government of general jurisdiction. It may act only when the Constitution grants it power, either explicitly or by necessary implication. Most MBE questions on separation of powers ask whether a federal statute is (i) a valid exercise of one of Congress’s powers or (ii) an unconstitutional overreach that violates federalism principles or individual rights.

Enumerated Powers of Congress

Article I, Section 8 lists most of Congress’s powers: to tax and spend, regulate commerce, declare war, raise and support armies, establish rules for citizenship and bankruptcy, coin money, and so on. Congress also has enforcement powers under the post–Civil War Amendments.

Key Term: Enumerated Powers
The specific powers granted to Congress by the Constitution, primarily in Article I, Section 8, plus enforcement clauses in the Thirteenth, Fourteenth, and Fifteenth Amendments.

The starting point for any MBE analysis is: “What is the source of congressional power?” If no enumerated (or enforcement) power fits, and the law is not necessary and proper to carry out another valid power, the statute is unconstitutional.

The Commerce Power

Article I, Section 8, Clause 3 authorizes Congress “to regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes.”

Key Term: Commerce Clause
The constitutional provision (Art. I, § 8, cl. 3) giving Congress power to regulate commerce with foreign nations, among the states, and with Indian tribes.

Modern doctrine allows Congress to regulate three broad categories:

• Channels of interstate commerce (the “pathways” of trade):
  • Highways, railroads, navigable waters, airspace, the internet.

Key Term: Channels of Interstate Commerce
The routes and infrastructure through which interstate economic activity moves, such as roads, waterways, airways, and communications networks.

• Instrumentalities of interstate commerce and persons or things in interstate commerce:
  • Trucks, ships, aircraft, trains; goods and people traveling across state lines.

Key Term: Instrumentalities of Interstate Commerce
The vehicles, persons, and things used to carry out interstate economic activity, such as cars, trucks, airplanes, and the goods and passengers they transport.

• Activities that substantially affect interstate commerce:
  • Both interstate and intrastate activity that, viewed in the aggregate, has a substantial economic effect on interstate markets.

For economic or commercial activity, Congress may regulate intrastate conduct if there is a rational basis to think that, in the aggregate, it substantially affects interstate commerce. Classic examples include:

• A farmer growing wheat for home consumption (affects national wheat prices in the aggregate).
• Intrastate cultivation and use of medical marijuana as part of a broader federal scheme regulating the national drug market.

For non-economic, non-commercial activity, the Court is much more skeptical. Congress may not rely on attenuated economic effects. The Supreme Court has struck down:

• A federal ban on possessing guns in school zones (mere possession near a school is not economic activity).
• A civil remedy for gender-motivated violence (crime is traditionally local; the statute targeted non-economic activity).

In these cases, the Court refused to pile inference upon inference to find a substantial effect.

Finally, Congress cannot use the Commerce Clause to regulate inactivity. In the Affordable Care Act case, the Court held that Congress could not force individuals to buy health insurance on the theory that not buying insurance affects commerce. Compelling people into commerce is beyond this power, though the same scheme was upheld under the taxing power.

On the MBE, ask:

1. Which of the three categories is Congress relying on?
2. Is the regulated activity economic or non-economic?
3. Is there a jurisdictional element or legislative findings tying the conduct to interstate commerce?

The Taxing and Spending Power

Article I, Section 8, Clause 1 authorizes Congress to “lay and collect Taxes” and “provide for the common Defence and general Welfare of the United States.”

Key Term: Taxing and Spending Power
Congress’s authority to levy taxes and spend federal funds for the general welfare (Art. I, § 8, cl. 1), subject to few substantive limits.

Key Term: General Welfare
In the Taxing and Spending Clause, a broad term interpreted to allow Congress to tax and spend in pursuit of any legitimate national interest, not confined to other enumerated powers.

The Taxing Power

Whenever Congress imposes a monetary exaction that is reasonably calculated to raise revenue, the Taxing Clause is usually the best answer. The Court is extremely deferential:

• A measure is a “tax” if it objectively looks like one (collected by IRS, produces revenue, no criminal stigma), even if Congress labels it a “penalty.”
• A tax can influence behavior (e.g., higher taxes on cigarettes) without ceasing to be a tax, so long as it is not a disguised criminal punishment.

On the MBE, if a statute imposes a nationwide monetary charge on certain conduct, and nothing else fits, the Taxing Power is often correct.

The Spending Power

The spending power is separate from, but housed in the same clause as, the taxing power. Congress may spend for the general welfare even when it could not directly regulate under the Commerce Clause.

Congress frequently uses conditional spending—offering federal funds to states if they accept certain conditions. This is central on the MBE. Conditions are valid if:

• The spending serves the general welfare.
• Conditions are stated unambiguously, so states know the consequences.
• Conditions are related (“germane”) to the federal interest in the particular program.
• The conditions do not require states to do something independently unconstitutional.
• The “inducement” is not so coercive that it becomes a “gun to the head.”

A classic example is conditioning highway funds on adoption of a 21-year-old drinking age: related to highway safety, clearly stated, and not coercive.

By contrast, threatening to withhold a huge existing funding stream to force states into a new scheme can be coercive and invalid.

The War and Defense Powers

Congress’s war and defense powers are found in several clauses:

• To declare war.
• To raise and support armies; provide and maintain a navy.
• To make rules for the regulation of the armed forces.

Congress may:

• Regulate the military during wartime and peacetime.
• Enact economic regulations linked to wartime needs (price controls, rationing).
• Authorize military courts for enemy combatants and enemy civilians.

But Congress may not subject civilian U.S. citizens to military trial when regular civilian courts are open and functioning.

The Enforcement Powers

The Thirteenth, Fourteenth, and Fifteenth Amendments each contain “enforcement” clauses authorizing Congress to adopt “appropriate legislation” to enforce those amendments.

Key Term: Enforcement Power
Congress’s authority under the Thirteenth, Fourteenth, and Fifteenth Amendments to pass laws preventing or remedying violations of the rights those amendments protect.

Thirteenth Amendment

The Thirteenth Amendment bans slavery and involuntary servitude. Its enforcement power is unique in two respects:

• It reaches private and state action.
• Congress may legislate against the “badges and incidents” of slavery, including racial discrimination by private actors.

This provides an independent basis to prohibit private race-based discrimination in some contexts.

Fourteenth Amendment

Section 1 of the Fourteenth Amendment binds the states, not private actors: “No State shall… deprive any person of life, liberty, or property, without due process of law; nor deny… equal protection of the laws.”

Section 5 gives Congress power to enforce these guarantees.

Key Term: Congruence and Proportionality
The requirement that § 5 legislation must be closely tailored to documented constitutional violations by states; the remedy must fit (be congruent and proportional to) the pattern of state violations identified by the Supreme Court.

Key limits:

• Congress may only address state (or local) action, not purely private conduct, under the Fourteenth and Fifteenth Amendments.
• Congress may remedy or prevent constitutional violations as defined by the Court; it may not redefine the scope of constitutional rights.

For § 5 legislation to be valid, there must be congruence and proportionality between the constitutional wrong and the remedy. For example:

• Congress could not require states to grant religious exemptions from neutral, generally applicable laws. That attempted to expand free-exercise rights beyond what the Court recognized.
• By contrast, Congress may subject states to damages suits for a pattern of intentional discrimination in employment, voting, or access to courts, where such discrimination itself violates the Fourteenth Amendment.

Fifteenth Amendment

The Fifteenth Amendment prohibits states and the federal government from denying the right to vote on account of race.

Congress may:

• Bar racial discrimination in voting by states and private actors.
• Require preclearance or other prophylactic measures, so long as they meet the congruence-and-proportionality standard.

The Necessary and Proper Clause

Article I, Section 8, Clause 18 gives Congress power “to make all Laws which shall be necessary and proper for carrying into Execution” its enumerated powers and those of other branches.

Key Term: Necessary and Proper Clause
The provision authorizing Congress to enact laws that are useful or convenient for carrying out its enumerated powers; it is not a free-standing source of power.

The clause is very broad. “Necessary” does not mean “absolutely indispensable”; it means “appropriate” or “plainly adapted” to a legitimate end. Examples:

• Creating a national bank to assist with taxation and borrowing.
• Federal criminal statutes prohibiting mail fraud or destruction of federal records.
• Administrative agencies implementing nationwide regulatory schemes.

On the MBE, however, an answer that says “Necessary and Proper Clause” alone is incomplete; it must be tied to some enumerated power (“necessary and proper to effectuate Congress’s power to regulate interstate commerce,” etc.).

Limits on Congressional Power

Congress’s powers are broad but not unlimited.

Key Term: Tenth Amendment
The amendment reserving to the states or the people powers not delegated to the United States by the Constitution, nor prohibited to the states.

Key Term: General Police Power
The general authority to legislate for the health, safety, welfare, and morals of citizens; possessed by states, but not by Congress, except in limited federal enclaves.

No General Federal Police Power

Congress has no general police power to legislate for public health, safety, or morals. Those are primarily state powers. The main exceptions—where Congress does have police-type power—are:

• The District of Columbia.
• Federal territories and possessions.
• Military bases and ships.
• Indian reservations.

Any MBE answer suggesting that Congress acted under its “general police power” is wrong.

Anti-Commandeering Principle

Key Term: Anti-Commandeering Principle
The rule that Congress may not require state legislatures or executive officials to enact, administer, or enforce federal regulatory programs.

Congress may not:

• Order state legislatures to pass particular laws.
• Require state executives or police to administer federal regulatory schemes.

It may, however:

• Regulate private parties directly.
• Apply generally applicable federal laws to states as employers or market participants.
• Induce states to adopt policies through valid conditional spending.

Delegation of Legislative Power

Congress may delegate broad authority to executive agencies if it supplies an intelligible principle guiding the exercise of the delegated power. This is an extremely forgiving standard; almost any policy guidance (e.g., act in the “public interest,” “fair and equitable” regulation) suffices.

Congress may not:

• Retain a legislative veto, i.e., reserve to itself the power for one house, both houses without presentment, or a committee to overturn executive actions without going through the full legislative process.
• Give executive power to officers who are under direct legislative control (e.g., appointed and removable by Congress).
• Circumvent the President’s role in lawmaking prescribed by the Presentment Clause.

Preemption and Supremacy

The Supremacy Clause (Article VI) states that the Constitution and valid federal laws “shall be the supreme Law of the Land,” binding judges in every state.

Key Term: Supremacy Clause
The constitutional provision that makes the Constitution, federal laws, and treaties supreme over conflicting state law.

Key Term: Preemption
The principle that valid federal law overrides conflicting state or local law; preemption may be express or implied.

When Congress validly legislates within its powers, state law that conflicts with federal law is preempted. Forms of preemption:

• Express preemption: The federal statute explicitly states that state laws on a particular subject are displaced. Express clauses are construed narrowly.

• Field preemption: Federal regulation is so pervasive that it appears Congress intended to occupy an entire field (e.g., certain aspects of immigration or federal currency), leaving no room for state regulation.

• Conflict preemption:

  • Impossibility: It is impossible to comply with both federal and state law.
  • Obstacle: State law stands as an obstacle to the accomplishment of a federal objective, even if compliance with both is technically possible.

Courts apply a presumption against preemption in areas of traditional state concern (health, safety, land use) absent clear congressional intent.

Remember: preemption is always about valid federal law. If Congress lacked authority to pass the statute, there is nothing to preempt state law.

Worked Example 1.1

Congress enacts a law prohibiting racial discrimination by restaurants serving interstate travelers. Is this law likely constitutional?

Answer:
Yes. Restaurants buy food that moves in interstate commerce and serve interstate travelers. Regulating their discriminatory practices is regulation of economic activity with a substantial effect on interstate commerce. Under the Commerce Clause, Congress may reach even local businesses when their activities, judged in the aggregate, substantially affect interstate markets.

Worked Example 1.2

Congress passes a statute requiring states to adopt a specific curriculum for public schools. Is this statute valid?

Answer:
No. Education is traditionally a state function. Congress cannot commandeer state legislatures and executive officials by directing them to enact and administer particular programs. This violates the Tenth Amendment’s anti-commandeering principle, even if Congress could have some indirect influence through spending conditions.

Worked Example 1.3

Congress offers states highway funds on the condition that they set the drinking age at 21. Is this constitutional?

Answer:
Yes. Congress is spending for the general welfare and attaching clear, related conditions. The condition (drinking age linked to highway safety) is germane to the purpose of the funds and does not coerce states by threatening catastrophic loss of existing funding. Conditional spending of this type is a standard, valid use of Congress’s spending power.

Worked Example 1.4

To address rising cybersecurity threats, Congress appropriates $10 billion to fund state “Cyber Response Units.” The statute authorizes the Department of Homeland Security to issue detailed rules and to select which state agencies receive grants, provided states agree to adopt federal cybersecurity standards for their networks. A state challenges the statute, arguing that Congress has delegated too much power and is commandeering state agencies.

Answer:
The statute is likely valid. Congress is spending for the general welfare in an area connected to national security and commerce. It may condition grants on states’ acceptance of federal standards, so long as the conditions are clear, related to the federal program, and not coercive. Delegating selection of recipients and implementation details to an agency is permissible because Congress has supplied an intelligible principle (cybersecurity protection). The program induces, but does not compel, state participation, so it does not violate the anti-commandeering principle.

Worked Example 1.5

Congress enacts a statute providing that no federal, state, or local government may enforce any law that “substantially burdens religious exercise” unless the government proves a compelling interest and narrow tailoring, even as to neutral, generally applicable laws. A state argues that, as applied to state and local governments, the statute exceeds Congress’s § 5 power under the Fourteenth Amendment.

Answer:
The state is correct. Section 5 allows Congress to enforce Fourteenth Amendment rights as defined by the Court, but not to redefine their substance. The Supreme Court has held that neutral, generally applicable laws do not violate the Free Exercise Clause. Imposing a strict-scrutiny standard across the board is not a congruent and proportional remedy for actual unconstitutional targeting of religion. As applied to states and localities, such a statute exceeds Congress’s enforcement power.

Exam Warning

Be alert for questions where Congress tries to regulate purely local, non-economic activity under the Commerce Clause—such as violent crime, family law, or education—without a strong economic component or jurisdictional hook. Also be wary of federal statutes that appear to direct state legislatures or executives to implement federal programs; these often violate the anti-commandeering principle.

Revision Tip

When analyzing a federal statute, first identify the enumerated or enforcement power on which Congress is relying, then ask whether the statute is “necessary and proper” to implement that power and whether any constitutional limits apply—especially the Tenth Amendment, the Bill of Rights, equal protection, and state sovereign interests.

Key Point Checklist

This article has covered the following key knowledge points:

• Congress is a government of limited, enumerated powers; it may act only when the Constitution grants it authority.
• The Commerce Clause allows regulation of (1) channels, (2) instrumentalities and persons or things in interstate commerce, and (3) activities that substantially affect interstate commerce, with tighter limits on non-economic activity.
• The Taxing Power permits Congress to impose taxes that reasonably raise revenue, even if they influence behavior.
• The Spending Power permits Congress to spend for the general welfare and attach clear, related, non-coercive conditions to federal funds.
• Congress’s war and defense powers support extensive regulation of the armed forces and wartime measures but do not allow military trials of civilians when civil courts are open.
• Enforcement powers under the Thirteenth, Fourteenth, and Fifteenth Amendments allow Congress to prevent and remedy constitutional violations, subject to the congruence-and-proportionality requirement and subject to state-action limits (except under the Thirteenth Amendment).
• The Necessary and Proper Clause lets Congress choose rational means to carry out its enumerated powers but is not an independent source of authority.
• Congress has no general police power (except over federal enclaves) and may not commandeer state legislatures or executives.
• Broad delegation to administrative agencies is permitted if Congress provides an intelligible principle; legislative vetoes and congressional control over executive officers’ functions are invalid.
• Under the Supremacy Clause, valid federal law preempts conflicting state law through express, field, or conflict preemption, subject to a presumption against preemption in traditional state areas.
• The Tenth Amendment and anti-commandeering principle are recurring federalism limits tested on the MBE.

Key Terms and Concepts

• Enumerated Powers
• Commerce Clause
• Channels of Interstate Commerce
• Instrumentalities of Interstate Commerce
• Taxing and Spending Power
• General Welfare
• Necessary and Proper Clause
• Enforcement Power
• Congruence and Proportionality
• Tenth Amendment
• General Police Power
• Anti-Commandeering Principle
• Supremacy Clause
• Preemption