State Governments Must Follow Which Type Of Laws

You’re sitting at a kitchen table in Colorado, legally lighting up a joint. On top of that, drive six hours east to Kansas, and that same act lands you in a cell. Cross the river from Washington into Idaho with a legally purchased handgun, and you might be a felon before you hit the state line.

It’s not a glitch. It’s the feature.

The United States wasn’t built as a single, unified legal monolith. It was built as a tension — a constant, negotiated argument between a national government and fifty semi-sovereign states. That argument is the only reason the map looks the way it does. And if you want to understand why state governments can do some* things but get stopped cold on others, you have to stop looking for a simple list of rules and start looking at the hierarchy.

What Is the Legal Hierarchy Binding State Governments

The short answer: state governments must follow the U.Constitution, valid federal statutes, and ratified treaties. That’s the ceiling. S. But the floor — the space where states actually operate — is defined by their own constitutions, their own statutes, and the vast reservoir of power the Tenth Amendment leaves them.

Let’s break the ceiling down first, because that’s where the fights happen.

The Supremacy Clause: Article VI, Clause 2

This is the atomic unit of American federalism. It says the Constitution, the laws of the United States made in pursuance thereof, and treaties made under the authority of the United States “shall be the supreme Law of the Land.” Judges in every state are bound thereby, anything in the constitution or laws of any state to the contrary notwithstanding.

Read that last phrase again. Anything in the constitution or laws of any state to the contrary notwithstanding.*

That means a state constitutional amendment — voted on by the people, signed by the governor, etched in marble — evaporates the moment it conflicts with a valid federal law. It doesn’t matter how popular the state law is. Practically speaking, it doesn’t matter if the state legislature passed it unanimously. Federal law wins.

But “valid federal law” is doing a lot of heavy lifting there. But congress can’t just pass anything. Think about it: it needs an enumerated power — commerce, taxation, war, postal roads, copyright, and a few others. If Congress oversteps, the Supremacy Clause doesn’t apply because the federal law was never “made in pursuance” of the Constitution to begin with. Consider this: it’s void. The states don’t have to follow it.

The Constitution Itself: Direct Commands on States

Here's the thing about the Constitution doesn’t just empower Congress. It directly commands states in a handful of specific ways.

• Article I, Section 10: States cannot coin money, emit bills of credit, make anything but gold and silver coin legal tender, pass bills of attainder, ex post facto laws, or laws impairing the obligation of contracts. They can’t grant titles of nobility. They can’t, without Congress’s consent, lay duties on imports or exports, keep troops or ships of war in peacetime, enter agreements with other states or foreign powers, or engage in war unless actually invaded.
• The Fourteenth Amendment: This is the big one. No state shall make or enforce any law which abridges the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.

That last sentence — the Equal Protection Clause — is the engine behind Brown v. Board*, Obergefell*, Roe (while it stood), and a thousand other cases where federal courts struck down state laws. It turns the Bill of Rights, which originally only bound the federal government, into a leash on state power through “incorporation.

Federal Statutes and the Commerce Clause

Most federal laws that states actually bump into day-to-day come from the Commerce Clause. Congress has the power “to regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes.”

For about sixty years — roughly 1937 to 1995 — the Supreme Court read “among the several States” so broadly that Congress could regulate almost anything that had a substantial economic effect, even if the activity was purely local. Day to day, wickard v. Filburn* let the feds regulate a farmer’s wheat grown for his own chickens because it affected the national market.

Then came United States v. Lopez* (1995). The Court said no: the Gun-Free School Zones Act exceeded the Commerce Power because carrying a gun near a school wasn’t economic activity. On top of that, united States v. Morrison* (2000) struck down parts of the Violence Against Women Act for the same reason.

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The pendulum swung back slightly with Gonzales v. Raich* (2005) — homegrown medical marijuana, even where state-legal, could be banned federally because it’s part of a larger regulatory scheme. But the message stuck: there is a limit. States don’t have to follow federal laws that Congress had no power to pass.

Treaties: The Forgotten Layer

Treaties ratified by the Senate are supreme law. Think about it: missouri v. Holland* (1920) established that a treaty can authorize Congress to pass laws it otherwise couldn’t — in that case, protecting migratory birds, a subject not clearly in Congress’s enumerated powers. The logic: the treaty power is its own font of authority.

But there’s a catch. A treaty cannot override the Constitution itself

and cannot be used to circumvent the Bill of Rights. Consider this: if a treaty were to violate the fundamental liberties of citizens, the Supreme Court has maintained that the Constitution remains the "supreme Law of the Land," sitting atop the hierarchy of treaties. This prevents the federal government from using international diplomacy as a loophole to erode domestic constitutional protections.

The Supremacy Clause: The Final Arbiter

The tension between federal and state authority is ultimately resolved by the Supremacy Clause of Article VI. In practice, it dictates that when a valid federal law and a conflicting state law collide, the federal law wins. This ensures that the United States functions as a single, cohesive nation rather than a loose confederation of fifty independent entities.

Still, "valid" is the operative word. For a federal law to trigger supremacy, it must be rooted in one of the enumerated powers—such as the Commerce Clause, the Taxing and Spending Clause, or the Fourteenth Amendment—discussed above. If Congress oversteps its constitutional bounds, the law is ultra vires* (beyond its power), and the states are not obligated to follow it.

Conclusion

The American federal system is not a static hierarchy, but a constant, living tug-of-war. Day to day, through the interplay of enumerated powers, the restrictive leash of the Fourteenth Amendment, and the ultimate refereeing of the Supreme Court, the Constitution seeks to balance national unity with local autonomy. It is a delicate equilibrium designed to prevent both the tyranny of a centralizing federal government and the chaos of fifty different sets of rules. While the boundaries of this power shift with every landmark Supreme Court decision, the fundamental architecture remains: a government of limited powers, intended to serve the people while respecting the sovereignty of the states.

The enduring genius of the American constitutional framework lies not in its rigidity, but in its capacity for principled evolution. Each generation faces new challenges—technological disruption, global interconnection, and shifting social norms—that test the boundaries of federal versus state authority. Yet the foundational architecture remains intact, providing a stable foundation upon which adaptation can occur without sacrificing core democratic principles.

The judiciary, particularly the Supreme Court, serves as the guardian of this balance. Through cases like McCulloch v. Day to day, maryland*, Gibbons v. Ogden*, and more recently, NFIB v. Sebelius*, the Court has consistently interpreted the Constitution's grant of powers with both breadth and restraint. It recognizes that effective governance requires flexibility in applying ancient principles to modern circumstances, while simultaneously ensuring that no level of government becomes so powerful as to threaten individual liberty or state sovereignty.

This dynamic equilibrium reflects the Framers' deep understanding of human nature and political reality. They crafted a system that acknowledges the necessity of unified national action on matters of broad concern—commerce, defense, foreign policy—while preserving space for local innovation and democratic experimentation. States remain laboratories of democracy, free to pursue policies that reflect their unique values and needs, provided they operate within constitutional bounds. Turns out it matters.

Looking forward, the challenge lies not in choosing between federal and state power, but in maintaining the mechanisms that allow these levels of government to check each other while advancing the common good. The Constitution's enduring strength stems from its ability to accommodate competing interests without collapsing into either anarchy or tyranny.

In this ongoing dance of federalism, neither level of government holds permanent ascendancy. Instead, they remain locked in a constitutional conversation—one that has lasted over two centuries and shows no signs of abating. This is not a flaw, but rather the very feature that ensures the American experiment continues to evolve while remaining true to its founding ideals of limited government, individual rights, and democratic self-governance.