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In the United States, who has the final say—the federal government in Washington, D.C., or your state government?
This guide unpacks a system of shared power, explains the constitutional rules that govern it, and explores the modern-day battlegrounds where the federal government and the states vie for authority.
Understanding American Federalism
To understand who has authority over what, you must first understand how power is divided in the United States. This blueprint, known as federalism, was a deliberate and revolutionary design choice by the framers of the Constitution that continues to define American political life.
What Is Federalism?
At its core, federalism is a system of government where two levels of government—a national government and smaller, regional governments (the states)—have authority and control over the same territory and the same people.
In the United States, this means you are simultaneously a citizen of your state and a citizen of the United States, and you must follow the laws of both. The Constitution established this system of “dual sovereignty,” in which the states surrendered some of their powers to the newly created federal government but retained a great deal of authority for themselves.
This design was a practical compromise born from hard-won experience. The first American government, established by the Articles of Confederation, was a loose league of powerful, sovereign states with a very weak central government.
This experiment proved disastrous. The national government lacked the power to tax, service the war debt, negotiate trade agreements, or resolve commercial disputes between states, leading to economic chaos and instability.
The founders, having fought a revolution against the tyranny of a powerful, centralized king, were wary of creating another overly dominant national government. Their solution was federalism: a stronger central government to handle national and international issues, while leaving most day-to-day governance in the hands of the states, which were seen as being closer and more responsive to the people.
Why Federalism Matters
This division of power is one of the most fundamental checks on government abuse. By ensuring that power is not concentrated at one level or in one branch, federalism makes it difficult for any single entity to gain absolute control, thereby reducing the risk of tyranny and protecting individual liberty.
The system was not designed to be frictionless. The overlapping jurisdictions and inherent tension between state and federal authority were intentional. These conflicts are the very mechanism through which the balance of power is constantly debated, negotiated, and redefined, ensuring that the government remains accountable to the people it serves.
Three Types of Government Powers
The U.S. Constitution sorts government responsibilities into three main categories of power. Understanding which powers go into which category is the key to answering the question, “who has authority?”
Enumerated Powers: The Federal Government’s Authority
The federal government is a government of limited and enumerated powers. This means it can only exercise the powers specifically granted to it by the Constitution. Most of these powers are listed in Article I, Section 8 of the Constitution.
They include responsibilities that are national in scope, things that one state alone cannot effectively manage. Key enumerated powers include:
To lay and collect Taxes, Duties, Imposts and Excises to pay debts and provide for the common defense and general welfare of the United States.
To regulate Commerce with foreign nations, among the several states, and with the Indian Tribes. This is the famous Commerce Clause, a major source of federal regulatory authority.
To coin Money and regulate its value, and to declare war.
To establish Post Offices and post Roads and to raise and support an Army and a Navy.
To make all Laws which shall be necessary and proper for carrying into execution the foregoing powers. Known as the Elastic Clause, this gives Congress the flexibility to pass laws not explicitly listed but deemed necessary to perform its duties, such as establishing a national bank.
Reserved Powers: The States’ Domain
The constitutional bedrock of state authority is the Tenth Amendment, which states: “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.”
This amendment acts as a constitutional boundary, affirming that states retain a broad range of powers over the daily lives of their citizens.
These reserved powers are often called the states’ “police powers“—the authority to regulate for the health, safety, morals, and general welfare of their residents. Concrete examples of reserved powers include:
- Creating public school systems and setting education standards
- Managing business and trade that occurs entirely within a state’s borders (intrastate commerce)
- Running elections and setting voter qualifications
- Establishing state and local police forces and overseeing state court systems
- Issuing licenses, such as for driving, marriage, or practicing professions like medicine and law
The Tenth Amendment and the “Necessary and Proper” Clause exist in a state of perpetual tension. They represent the two opposing poles of the federalism debate.
When the Supreme Court interprets federal power expansively under the Elastic Clause, the domain of powers reserved to the states under the Tenth Amendment necessarily shrinks. Conversely, when the Court emphasizes the limits imposed by the Tenth Amendment, it constrains what Congress can constitutionally deem “necessary and proper.”
Nearly every major dispute over the scope of government power in American history has been a battle between these two foundational principles.
Concurrent Powers: Shared Authority
Concurrent powers are those that both the federal and state governments can exercise at the same time, in the same territory. These are areas of shared responsibility where both levels of government have a legitimate interest.
Key examples of concurrent powers include:
- The power to tax individuals and businesses and to borrow money
- The authority to build roads and other infrastructure
- The power to establish courts at both the federal and state levels
- The ability to make and enforce laws and define crimes
Because both governments operate in this “shared sandbox,” the area of concurrent powers is frequently where conflicts arise. For example, whose laws prevail when federal and state criminal statutes overlap? This is where the constitutional “rules of the game” become critically important.
Division of Governmental Powers
The following table provides a clear summary of how government powers are divided in the U.S. federal system.
| Enumerated Powers (Federal Only) | Concurrent Powers (Shared) | Reserved Powers (State Only) |
|---|---|---|
| Declare War | Levy and Collect Taxes | Establish Local Governments |
| Coin Money & Regulate its Value | Borrow Money | Regulate Intrastate Commerce |
| Regulate Interstate & Foreign Commerce | Establish Courts | Conduct Elections & Set Voter Qualifications |
| Establish Post Offices | Make and Enforce Laws | Ratify Constitutional Amendments |
| Raise and Support Armies & a Navy | Charter Banks & Corporations | Provide for Public Health, Safety, and Welfare |
| Conduct Foreign Relations & Make Treaties | Build Roads & Infrastructure | Regulate Marriage, Divorce, & Adoption |
| Establish Rules of Naturalization | Take Property for Public Use (Eminent Domain) | Issue Licenses (Driving, Professional, etc.) |
Constitutional Rules of Conflict
When federal and state laws clash, the Constitution provides a rulebook for resolving the dispute. Three clauses in particular act as the primary referees in the ongoing power struggle: the Supremacy Clause, the Commerce Clause, and the Tenth Amendment.
How these clauses are interpreted by the courts determines the outcome of federal-state conflicts and defines the boundaries of power for each level of government.
The Supremacy Clause
Article VI, Clause 2 of the Constitution contains what is known as the Supremacy Clause. It declares that the Constitution, and the federal laws and treaties made “in Pursuance thereof,” are the “supreme Law of the Land.”
This means that if a state law is in direct conflict with a valid federal law, the federal law prevails, and state courts and officials are bound to follow it.
This clause is the foundation for the legal doctrine of preemption, which is the principle that a higher authority of law can displace the law of a lower authority when the two conflict. Preemption can occur in several ways:
Express Preemption: This is the most straightforward type. It occurs when Congress includes explicit language in a federal statute stating its intent to preempt, or override, any state laws in that specific area.
Implied Preemption: This form is not explicitly stated but is inferred from the structure and purpose of a federal law. It comes in two main varieties:
Conflict Preemption: This happens when it’s physically impossible to comply with both the federal and state regulations, or when a state law “stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress.”
Field Preemption: This occurs when the federal government has created a regulatory scheme so comprehensive and pervasive that courts can infer Congress intended to “occupy the field,” leaving no room for state regulation on the same subject.
However, the Supremacy Clause is not an unlimited grant of power. Its authority is conditional. The clause specifies that only federal laws made “in Pursuance” of the Constitution are supreme.
This critical phrase means that a federal law must first be constitutional—that is, based on one of Congress’s enumerated powers—before it can preempt state law. As Alexander Hamilton argued in The Federalist Papers, a legislative act contrary to the Constitution is void.
Therefore, a state can challenge a federal law by arguing that Congress overstepped its constitutional authority. If the state wins that argument, the federal law is struck down, and the Supremacy Clause becomes irrelevant. The first question is always whether the federal government had the power to act in the first place.
The Commerce Clause
Article I, Section 8, Clause 3 of the Constitution gives Congress the power “to regulate Commerce with foreign Nations, and among the several States.” This Commerce Clause has become one of the most significant and far-reaching sources of federal legislative power.
The interpretation of this clause is not static; it has been a primary battleground for competing political ideologies about the proper role of the federal government.
For much of the nation’s early history, “commerce” was interpreted narrowly to mean the trade, exchange, and transportation of goods across state lines. However, during the Great Depression of the 1930s, the Supreme Court began to adopt a much broader view to allow for President Franklin D. Roosevelt’s New Deal programs.
The Court established that Congress could regulate any local, intrastate activity that had a “substantial economic effect” on interstate commerce.
This interpretation reached its zenith in the 1942 case of Wickard v. Filburn. The Court ruled that a farmer, Roscoe Filburn, who grew wheat on his own farm for his own family’s consumption, could be regulated by the federal government.
The reasoning was that by growing his own wheat, he was not buying it on the open market. While his individual action was trivial, the cumulative effect of many farmers doing the same would substantially affect the national price of wheat and thus interstate commerce.
This decision dramatically expanded federal power, allowing Congress to regulate a vast range of activities previously considered local.
This broad interpretation held for decades until the 1995 case United States v. Lopez. In Lopez, the Supreme Court struck down the federal Gun-Free School Zones Act, ruling for the first time in nearly 60 years that Congress had exceeded its Commerce Clause power.
The Court reasoned that possessing a gun in a local school zone was not an economic activity and had no substantial effect on interstate commerce. This decision signaled a shift, with the Court seeking to draw a clearer line “between what is truly national and what is truly local.”
The Commerce Clause also has a “negative” or “Dormant” implication. This doctrine prohibits states from passing legislation that improperly discriminates against or burdens interstate commerce, even in the absence of federal law on the subject. It serves to prevent states from engaging in economic protectionism that would harm the national market.
The Tenth Amendment
Positioned as the constitutional safeguard for states’ rights, the Tenth Amendment serves as the primary boundary line against federal overreach. It was added to the Constitution as part of the Bill of Rights to allay the fears of Anti-Federalists who worried that the new national government would absorb all powers and obliterate the states.
In modern constitutional law, the most important doctrine derived from the Tenth Amendment is the “anti-commandeering” principle. This rule, established by the Supreme Court in cases like New York v. United States (1992) and Printz v. United States (1997), holds that the federal government cannot “commandeer” state governments.
This means Congress cannot force a state’s legislature to pass a specific law, nor can it compel a state’s executive officials (like police officers) to enforce a federal regulatory program.
The Court has reasoned that forcing states to implement federal policy blurs the lines of political accountability; if citizens are unhappy with a policy, they may not know whether to blame their state officials or the federal government.
This doctrine provides a powerful check on federal power, preserving a sphere of autonomy for state governments to control their own resources and personnel.
Modern Case Studies
The constitutional principles of federalism are at the center of the most contentious political and legal debates of our time. Examining modern case studies reveals how the tug-of-war between federal and state power plays out in the real world, affecting policy on everything from public health to personal liberty.
Marijuana Legalization
Perhaps no issue illustrates the modern federal-state conflict more vividly than marijuana legalization. There’s a direct and unambiguous clash: under the federal Controlled Substances Act, marijuana is classified as a Schedule I drug, making its possession, cultivation, and sale illegal nationwide.
Yet, a large and growing number of states have legalized marijuana for either medical or recreational use, creating a regulated industry that is legal under state law but a federal crime.
This situation creates a legal paradox. How can states do this if federal law is supreme? The answer lies in the Tenth Amendment’s anti-commandeering doctrine.
The federal government cannot force state and local police to arrest people for violating federal marijuana laws. States are not attempting to nullify federal law; they are simply repealing their own parallel state-level prohibitions and choosing not to expend their own resources to enforce the federal ban.
This has led to a situation where the de jure (legal) reality is that federal law is supreme, but the de facto (practical) reality is quite different. The federal government lacks the resources and, often, the political will to enforce a nationwide prohibition against the wishes of a majority of states.
This has resulted in a fragile truce, exemplified by policies like the 2013 “Cole Memo,” in which the Department of Justice advised federal prosecutors to deprioritize enforcement against individuals and businesses complying with “robust” state regulatory systems. (The Cole Memo was rescinded in 2018 but influenced enforcement practices nonetheless.)
However, this enforcement discretion is not law and can change with a new administration. The Supremacy Clause means that federal agents can, at any time, raid and prosecute state-licensed marijuana businesses, which remain in violation of federal law.
This ongoing conflict creates profound uncertainty and practical problems, such as the inability of these legal businesses to access federally regulated banking services.
Environmental Regulation: California’s Special Role
Environmental regulation is another major arena for federal-state conflict. To create a uniform national market and prevent a chaotic patchwork of 50 different standards for automakers, the federal Clean Air Act generally preempts states from setting their own new motor vehicle emissions standards. This is a clear example of Congress using its Commerce Clause power to establish a single federal rule.
However, the Act includes a unique exception for California. Recognizing the state’s early leadership in combating air pollution and its “compelling and extraordinary conditions” related to smog, Section 209 of the Act allows California to apply to the Environmental Protection Agency for a waiver to set its own, stricter emissions standards.
The EPA must grant this waiver unless it finds California’s standards are not needed or are technologically infeasible.
Furthermore, Section 177 of the Act allows other states to adopt California’s stricter standards as their own, once a waiver is granted. As of 2025, 17 states and the District of Columbia have done so, representing over 40% of the U.S. new vehicle market.
This effectively allows California to act as a national leader, pushing federal policy and the auto industry toward more stringent environmental protections.
This waiver has become a major political football, with Democratic administrations typically granting waivers (including for regulations promoting electric vehicles) and Republican administrations attempting to revoke them, arguing they overstep state authority.
This demonstrates how the balance of federalism can be directly influenced by partisan politics at the national level.
Healthcare: The Affordable Care Act Battles
The 2010 Patient Protection and Affordable Care Act triggered some of the most significant federalism battles of the 21st century. States, primarily led by Republican attorneys general, launched a series of legal challenges to the law, arguing that Congress had overstepped its constitutional powers.
The first major challenge, National Federation of Independent Business v. Sebelius (2012), targeted two key provisions:
The Individual Mandate: The states argued that the requirement for nearly all Americans to obtain health insurance or pay a penalty exceeded Congress’s authority under the Commerce Clause. They contended that Congress could regulate existing economic activity but could not compel individuals to engage in commerce by buying a product.
In a landmark ruling, the Supreme Court agreed, holding that the Commerce Clause did not justify the mandate. However, the Court upheld the provision under a different enumerated power: Congress’s power to tax.
The Medicaid Expansion: The ACA required states to expand their Medicaid programs to cover more low-income adults or risk losing all of their existing federal Medicaid funding. The Court found this to be unconstitutionally coercive.
It ruled that the federal government could use its spending power to encourage states to adopt certain policies, but it could not put a “gun to the head” of the states by threatening to take away massive, pre-existing funds. The Court made the Medicaid expansion optional for states, a major victory for state sovereignty.
Years later, after Congress reduced the tax penalty for the individual mandate to zero, Texas led another lawsuit, California v. Texas, arguing that since the mandate could no longer be justified as a tax, it was unconstitutional, and therefore the entire ACA must fall.
In 2021, the Supreme Court dismissed this case on procedural grounds, ruling that the states lacked “standing” to sue because an unenforceable mandate with no penalty caused them no concrete harm.
These cases show states using the federal court system as a primary tool to wage partisan battles over national policy, turning constitutional questions of federalism into high-stakes political showdowns.
States as Laboratories of Democracy
Beyond the conflicts and legal battles, federalism offers a profound benefit to the American system of governance: it fosters innovation. This idea is best captured by the famous metaphor of states as “laboratories of democracy,” a concept that highlights the positive role of state autonomy in a large and diverse nation.
Innovation from the Ground Up
The phrase was coined by Supreme Court Justice Louis D. Brandeis in a 1932 dissenting opinion. He wrote, “It is one of the happy incidents of the federal system that a single courageous state may, if its citizens choose, serve as a laboratory; and try novel social and economic experiments without risk to the rest of the country.”
The logic is powerful. Federalism allows 50 different states to test new policy solutions to common problems on a smaller, manageable scale. If a new policy proves successful, it can serve as a model for other states and even for the federal government to adopt.
If it fails, the negative consequences are contained within that one state, preventing a nationwide disaster. This process of policy diffusion is a core strength of the federal system.
History is filled with examples of this principle in action:
Women’s Suffrage: Wyoming granted women the right to vote in 1869, more than 50 years before the 19th Amendment made it the law of the land.
Welfare Reform: Policy experiments in states like Wisconsin during the 1990s provided a blueprint for the landmark federal welfare reform legislation of 1996.
Marriage Equality: The movement for same-sex marriage began in state courts and legislatures, building momentum state by state before the Supreme Court’s 2015 ruling in Obergefell v. Hodges established it as a national right.
Healthcare Reform: The Massachusetts healthcare reform law of 2006, signed by then-Governor Mitt Romney, included an individual mandate and insurance exchanges that served as a key model for the federal Affordable Care Act.
Competition and Its Consequences
The “laboratories” model is not without its critics or potential downsides. State competition can sometimes lead to a “race to the bottom,” where states compete to attract businesses by lowering environmental standards, cutting taxes, or reducing worker protections, potentially to the detriment of the public good.
Furthermore, some scholars argue that states are often not well-equipped to be true innovators, hampered by limited budgets, short legislative sessions, and a lack of expertise, making them more likely to copy policies from other jurisdictions than to invent their own.
The greatest value of these state laboratories is their ability to accommodate the nation’s immense diversity. Federalism allows different communities to enact policies that reflect their unique local values, needs, and priorities.
A policy that works well for a large, urban state like California might be a poor fit for a rural state like Wyoming. By allowing for this variation, federalism provides a crucial safety valve, enabling a peaceful coexistence of different policy regimes that would be impossible if every decision had to be a one-size-fits-all solution for the entire country.
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