The relation of nation and states in a federal system - Supr...

Learning Outcomes

This article explains the relation of nation and states in a federal system, focusing on the Supremacy Clause and federal preemption, including:

• How the Supremacy Clause operates on exams, what counts as “supreme” federal law (Constitution, statutes, treaties, regulations), and how those sources interact with conflicting state constitutions, statutes, and local ordinances.
• The recognized categories of preemption—express, implied field, impossibility conflict, and obstacle preemption—and how courts infer congressional intent from statutory text, structure, and purpose in typical MBE-style multiple-choice questions.
• A step-by-step method for spotting preemption issues, organizing your analysis, and clearly stating whether state law is valid, partially displaced, or fully invalidated when federal and state regimes overlap.
• How preemption interacts with state police powers in traditional areas such as health, safety, and welfare, and how the presumption against preemption shapes the outcome where Congress’s intent is ambiguous.
• The relationship between preemption and the Dormant Commerce Clause, including when state regulation of interstate commerce is barred outright, permitted with federal consent, or allowed under the market participant doctrine.
• Key exam traps, such as confusing preemption with unconstitutional commandeering, assuming that any overlap automatically invalidates state law, or ignoring savings clauses and other statutory language that preserves concurrent state authority.

MBE Syllabus

For the MBE, you are required to understand the constitutional allocation of authority between federal and state governments, with a focus on the following syllabus points:

• The Supremacy Clause and its effect on conflicts between federal and state law
• Federal preemption: express preemption, implied field preemption, and implied conflict/obstacle preemption
• The presumption against preemption in traditional state police-power fields (health, safety, and welfare)
• The distinction between exclusive federal powers and concurrent powers shared with the states
• The limits on state authority when valid federal law exists in the same regulatory area
• Exceptions and special doctrines: congressional consent to state regulation and the market participant doctrine

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. If a valid federal law and a state law directly conflict, which law prevails?
   1. The state law
   2. The federal law
   3. The law enacted most recently
   4. The law with the broader scope
2. Which of the following is NOT a recognized form of federal preemption?
   1. Express preemption
   2. Field preemption
   3. Conflict preemption
   4. Police power preemption
3. Congress passes a federal law regulating food labeling. A state passes a stricter labeling law on the same subject. The federal law contains a clause stating, "States may not impose any additional requirements." What is the likely result?
   1. Both laws apply
   2. Only the state law applies
   3. Only the federal law applies
   4. Neither law applies
4. When may a state law survive even if it touches on an area regulated by federal law?
   1. If Congress expressly allows state regulation
   2. If the state law is stricter
   3. If the state law is older
   4. If the state law is more popular

Introduction

The U.S. Constitution creates a federal system in which both the national government and the states may legislate. Many powers are concurrent: both levels can, for example, tax, regulate business, and create courts. Others are exclusively federal (such as coining money, making treaties, and naturalization), and some regulatory space is left primarily to the states (health, safety, and general welfare).

Whenever both levels of government legislate in the same area, the risk of conflict arises. The Supremacy Clause and the doctrine of preemption provide the rules for resolving that conflict.

Key Term: Supremacy Clause
The provision in Article VI, Clause 2 of the U.S. Constitution stating that the Constitution, federal laws made pursuant to it, and treaties are the “supreme Law of the Land,” binding state judges and overriding conflicting state law.

A few structural ideas help orient the analysis:

Key Term: Exclusive Federal Powers
Powers that belong only to the federal government (e.g., treaty power, coinage of money, declaration of war, foreign affairs). States may not exercise them at all.

Key Term: Concurrent Powers
Powers that both the federal and state governments may exercise (e.g., taxation, general business regulation, many aspects of criminal law). In these areas, federal law can preempt state law, but does not automatically do so.

The Supremacy Clause does not itself give Congress new substantive powers. It simply says that when Congress acts within its enumerated powers and within constitutional limits, federal law is supreme over inconsistent state and local law.

Key Term: Preemption
The principle that valid federal law supersedes or displaces state or local law when the two conflict, when Congress intends to occupy a field, or when state law frustrates federal objectives.

Preemption questions are heavily tested on the MBE because they require precise reading of statutory text and careful application of federalism principles. The key is to move step-by-step and avoid assuming that any overlap automatically results in preemption.

The Supremacy Clause: Federal Law Is Supreme

The Supremacy Clause provides that:

• The U.S. Constitution
• Federal statutes enacted pursuant to the Constitution
• Treaties made under the authority of the United States
• Valid federal regulations (as exercises of delegated statutory power)

are the supreme law of the land. State constitutions, statutes, regulations, and local ordinances must yield where there is a conflict.

Two important points for exam purposes:

• Federal law must itself be valid. If Congress exceeds its enumerated powers, the statute is unconstitutional and cannot preempt anything.

• State judges are bound by federal law. A state court cannot decline to enforce a federal right simply because it disagrees with federal policy or wants to shield particular state actors (e.g., prison guards) from federal suits.

When there is a direct conflict between a valid federal statute and a state law—so that one commands what the other forbids, or vice versa—the state law is invalid “to the extent of the conflict.” It may remain valid as applied to situations not covered by federal law, but it cannot contradict the federal rule.

Types of Federal Preemption

Preemption is primarily a question of congressional intent. The Supreme Court has grouped the doctrine into categories that often overlap on MBE questions.

1. Express Preemption

Congress can expressly state its intent to displace state law in statutory text.

Key Term: Express Preemption
Preemption that occurs when a federal statute includes explicit language that state laws on a particular subject are displaced or superseded.

Typical express preemption clauses look like:

• “No State may establish or continue in effect any requirement with respect to ___ that is different from, or in addition to, the requirements of this Act.”
• “States are prohibited from regulating ___.”

On the MBE, if you see clear statutory language like this, courts will generally enforce it. However, an express preemption clause is construed narrowly: it preempts only what it actually covers.

Example: A federal statute preempts state “requirements based on smoking and health” in cigarette advertising. A state consumer fraud law targeting deceptive “light” and “low tar” advertisements was held not preempted because it targeted deception, not smoking and health directly. The express clause did not reach that state cause of action.

2. Implied Preemption

Even without explicit language, Congress can impliedly preempt state law. There are two main forms:

Key Term: Implied Preemption
Preemption that is inferred from the structure and purpose of federal law, even in the absence of explicit preemption language.

• Field Preemption – Congress has so thoroughly regulated a subject that it intends to occupy the entire field, leaving no room for any state law.
• Conflict Preemption – State law conflicts with federal law, either because it is impossible to comply with both, or because the state law stands as an obstacle to federal purposes.

Key Term: Field Preemption
Implied preemption inferred when federal regulation in an area is so pervasive, or the federal interest so dominant, that Congress is understood to have left no room for supplementary state regulation.

Indicators of field preemption on the exam:

• A comprehensive federal regulatory scheme
• Creation of a federal agency with broad authority over the area
• Sensitive national concerns (immigration status, foreign affairs, certain aspects of nuclear safety)

Example: Congress has enacted an extensive system for registering and regulating noncitizens. A state statute that creates its own registration crimes or allows state officers to arrest noncitizens on immigration grounds beyond what federal law allows is likely field-preempted.

Key Term: Conflict Preemption
Preemption that occurs when compliance with both federal and state law is impossible, or when state law frustrates the objectives or methods chosen by Congress.

Conflict preemption arises in two ways:

1. Impossibility – It is literally impossible to comply with both federal and state requirements.
2. Obstacle (or purposes-and-objectives) preemption – Even if dual compliance is possible, the state law interferes with the accomplishment of federal goals.

Because obstacle preemption is especially fact-sensitive, it is often tested with fact-intensive fact patterns.

3. Obstacle Preemption

Obstacle preemption is a subset of conflict preemption.

Key Term: Obstacle Preemption
Preemption that arises when state law poses an obstacle to the full realization of Congress’s purposes and objectives under federal law, even if compliance with both sets of rules is technically possible.

Classic examples include:

• A state law that effectively nullifies federal bankruptcy’s “fresh start” by continuing to penalize discharged debtors (e.g., by permanently suspending their driver’s licenses despite a bankruptcy discharge of the judgment).
• State procedures that make it practically impossible to enforce federal rights that Congress intended to be vindicated in state courts.

Obstacle preemption does not require that Congress use the best possible regulatory means; it focuses on whether state law undermines the means Congress did choose.

When Does Preemption Apply

Preemption analysis begins only if federal law is valid and Congress has acted in the relevant area. If Congress has not legislated at all, states may regulate under their retained police powers.

Key Term: Presumption Against Preemption
The interpretive principle that, especially in areas of traditional state police power (health, safety, welfare), courts presume Congress did not intend to preempt state law unless that intent is clear and manifest.

On MBE questions, move through this checklist:

1. Is the federal law valid?

   • Confirm that Congress is acting within an enumerated power (e.g., Commerce Clause, Taxing and Spending, immigration, bankruptcy).

2. Is there express preemption language?

   • Carefully read the clause; does it cover the kind of state law at issue, or only certain subjects (e.g., labeling but not tort suits)?

3. If no express preemption, is there field preemption?

   • Look for comprehensive federal regulation, a dominant federal interest, and a federal agency structure that suggests exclusivity.

4. If not, is there conflict or obstacle preemption?

   • Ask:
     • Would compliance with both sets of rules be impossible?
     • Even if possible, does the state rule frustrate or significantly interfere with a federal purpose?

Remember also that:

• Overlap alone is not enough. Two laws can regulate the same subject without preemption if they are compatible.
• States may often impose more stringent standards than federal law unless Congress has specifically prohibited additional requirements.

Key Term: Federal Consent
Congressional authorization that permits states to regulate in ways that would otherwise be preempted, or to discriminate against interstate commerce in ways that would otherwise violate the Dormant Commerce Clause.

Congress can expressly allow state regulation that would otherwise be preempted or would violate the Dormant Commerce Clause. When Congress gives such consent, a state law that fits within the authorization will be valid even if it burdens interstate commerce or touches on a heavily regulated area.

Federalism Limits: Preemption vs. Commandeering

It is important to distinguish preemption (which is permitted) from commandeering (which is not).

• Preemption simply invalidates state rules that conflict with federal law.
• Commandeering occurs when Congress tries to order states or state officials to enact or administer federal regulatory programs (e.g., requiring state legislatures to pass certain laws).

The Supremacy Clause authorizes preemption, not commandeering. On a multiple-choice question, a federal statute that tells states what they may not do in a given area is likely preemption; a statute that commands state legislatures or executives to regulate or enforce federal schemes is more likely an unconstitutional commandeering attempt.

Exceptions and Special Doctrines

Federal Consent

As noted, Congress may sometimes invite state regulation in an area where state law would otherwise be preempted or would infringe the Dormant Commerce Clause. Examples include statutes that allow states to regulate certain aspects of insurance or authorize specific state taxation of interstate activities.

The key MBE point: if a federal statute clearly authorizes particular state regulation, that authorization generally defeats preemption and Dormant Commerce Clause objections, so long as the state stays within the scope of the authorization.

Market Participant Doctrine

Key Term: Market Participant Doctrine
The principle that when a state acts as a buyer or seller in the market (rather than as a regulator), it may favor its own residents in that market activity without violating the Dormant Commerce Clause.

When a state is purchasing or selling goods or services—acting like any private market actor—it can sometimes treat in-state and out-of-state participants differently (for example, giving price preferences to in-state buyers of state-owned resources).

This doctrine is mainly a Dormant Commerce Clause exception. It does not insulate a state from preemption when Congress has legislated: if a federal statute directly forbids certain conduct by “any person,” a state cannot violate that statute merely by claiming it is acting as a market participant.

Also, note the limits:

• A state cannot rely on the market participant doctrine to impose downstream regulations on private parties that go beyond its own market role.
• If the state is exercising regulatory power, not simply bargaining as a buyer or seller, the doctrine does not apply.

Worked Example 1.1

A federal law sets minimum safety standards for car emissions and states, "No state may adopt or enforce any standard relating to emissions that is different from the federal standard." State X passes a law requiring stricter emissions controls.

Question: Is State X’s law valid?

Answer:
No. The federal law expressly preempts any state standard “relating to emissions” that is different from the federal standard. Because State X’s law imposes a stricter emissions requirement, it is displaced by express preemption under the Supremacy Clause.

Worked Example 1.2

Congress passes a federal law regulating food labeling but does not mention state law. State Y enacts a law requiring additional disclosures on food labels.

Question: Is State Y’s law valid?

Answer:
It depends. The court would first ask whether the federal scheme is so comprehensive that Congress intended to occupy the entire field of food labeling. If so, State Y’s law would be field-preempted. If the federal regulation is not comprehensive and the state law neither contradicts federal requirements nor frustrates federal objectives (for example, the federal law sets a floor and allows more information), State Y’s law may coexist with federal law.

Worked Example 1.3

Federal law requires all prescription drug labels to contain Warning A and explicitly allows manufacturers to “strengthen warnings consistent with the purposes of this Act” without prior FDA approval. State Z tort law imposes liability on manufacturers who fail to add Warning B, which goes beyond Warning A.

Question: Is State Z’s failure-to-warn law preempted?

Answer:
Probably not. There is no impossibility: manufacturers can comply with both the federal minimum (Warning A) and the state tort duty (add Warning B), especially because federal regulations allow strengthening warnings without prior approval. Nor does the state law appear to frustrate federal objectives, which include consumer safety. Absent clear congressional intent to occupy the field or forbid additional warnings, the presumption against preemption supports allowing the state law.

Worked Example 1.4

Federal bankruptcy law discharges certain auto accident judgments to give debtors a fresh start. A state law provides that a driver’s license will be suspended until such a judgment is paid, even if the debtor has received a bankruptcy discharge.

Question: Is the state license-suspension law preempted?

Answer:
Yes. Although a debtor technically could comply with both laws by paying the judgment, the state law stands as an obstacle to the federal purpose of providing a fresh start after bankruptcy. The continued suspension of the license undermines the relief Congress intended, so the state law is preempted under obstacle preemption.

Worked Example 1.5

Congress enacts a detailed system for licensing nuclear power plants and nuclear waste disposal, administered by a federal agency. A state passes an additional law imposing separate state licensing requirements on nuclear waste facilities.

Question: Is the state law preempted?

Answer:
Likely yes. The comprehensive federal regulatory regime and the need for nationwide uniformity in nuclear safety strongly suggest Congress intended to occupy the field. Even if the state’s requirements aim at safety, they intrude into an area where federal regulation is exclusive. This is classic field preemption.

Exam Warning

Courts will not find preemption lightly, particularly in fields historically regulated by the states, such as health and safety. The presumption is against preemption unless Congress’s intent to displace state law is clear. On MBE questions, do not jump to preemption merely because both levels of government regulate the same subject.

Revision Tip

Start by reading the federal statute carefully. Look for express preemption clauses, savings clauses, and language that reveals congressional purpose. If there is no express clause, ask whether Congress has clearly occupied the field, and then analyze whether there is an impossibility or obstacle-type conflict.

Summary

The Supremacy Clause establishes that valid federal law is the supreme law of the land and binds state courts and officials. Preemption is the mechanism by which federal law displaces conflicting state law. It may be:

• Express, via clear statutory language
• Implied through field preemption, when Congress occupies an entire regulatory area
• Implied through conflict or obstacle preemption, when state law makes compliance with federal law impossible or frustrates federal objectives

States retain broad police powers and may regulate alongside federal law unless Congress clearly indicates otherwise. Courts apply a presumption against preemption in traditional state fields. Preemption is distinct from commandeering: Congress may invalidate conflicting state rules but may not force states to legislate or administer federal programs.

Congress may also permit state regulation by giving federal consent, and states acting as market participants have additional leeway under the Dormant Commerce Clause, though they remain subject to federal statutes. On the MBE, careful reading of statutory text, attention to congressional purpose, and methodical application of these doctrines will allow you to determine whether a state law survives or is preempted.

Key Point Checklist

This article has covered the following key knowledge points:

• The Supremacy Clause makes the Constitution, valid federal statutes, treaties, and regulations supreme over conflicting state law.
• Many powers are concurrent; in these areas, federal law may preempt, but does not automatically displace, state law.
• Express preemption occurs when Congress clearly states that state law on a subject is displaced.
• Implied preemption includes field preemption (Congress occupies the field) and conflict preemption.
• Conflict preemption exists when it is impossible to comply with both laws, or when state law frustrates federal objectives (obstacle preemption).
• Courts apply a presumption against preemption in areas of traditional state police power unless Congress’s intent to preempt is “clear and manifest.”
• Congress may authorize states to regulate in areas that would otherwise be preempted or would violate the Dormant Commerce Clause.
• The market participant doctrine allows states acting as buyers or sellers (rather than regulators) to favor their own citizens without violating the Dormant Commerce Clause, though federal statutes can still preempt such conduct.
• Preemption is distinct from unconstitutional commandeering; the former invalidates conflicting state law, while the latter inappropriately forces states to legislate or administer federal law.

Key Terms and Concepts

• Supremacy Clause
• Preemption
• Express Preemption
• Implied Preemption
• Field Preemption
• Conflict Preemption
• Obstacle Preemption
• Presumption Against Preemption
• Exclusive Federal Powers
• Concurrent Powers
• Federal Consent
• Market Participant Doctrine