NFIB v. Sebelius: Mandate as Tax and Medicaid Expansion

In NFIB v. Sebelius, decided 5–4 on June 28, 2012, the Supreme Court upheld the Affordable Care Act’s individual mandate as a valid exercise of Congress’s taxing power, rejected it as an exercise of the Commerce Clause, and made the ACA’s Medicaid expansion optional for states by striking down the mechanism Congress had used to enforce it. Chief Justice John Roberts wrote the controlling opinion, and the ruling drew new outer limits around two of Congress’s most important powers in a single decision.¹

Who Sued and What They Challenged

Congress passed the Patient Protection and Affordable Care Act in March 2010. Two provisions drew immediate constitutional attack. The individual mandate required most Americans to maintain health insurance or pay a penalty. The Medicaid expansion required states to extend Medicaid coverage to a much larger population or risk losing all of their existing federal Medicaid funding.²

Twenty-six states, the National Federation of Independent Business, and several individuals sued in federal court, naming Health and Human Services Secretary Kathleen Sebelius as the lead defendant.³ Lower courts split. The Supreme Court set the case for three days of oral argument in March 2012, an unusually long schedule that reflected what was at stake.

The Individual Mandate: Not Commerce, but a Tax

The government’s first argument was that the mandate fit within Congress’s power to regulate interstate commerce. The national healthcare market is enormous, uninsured people shift billions in costs to hospitals and insurers, and Congress can reach economic activity that substantially affects interstate commerce.

Roberts rejected the argument. In his view, the Commerce Clause lets Congress regulate people already participating in commerce, but not force people into commerce in the first place. Someone who chose not to buy insurance was engaged in inactivity, not activity. If Congress could compel purchases on the theory that a person would eventually enter a given market, there was no logical stopping point.³ The oral arguments had produced the broccoli hypothetical: under the government’s theory, Congress could order everyone to buy broccoli. The majority found that kind of authority incompatible with a government of limited, enumerated powers.

The government also pointed to the Necessary and Proper Clause, arguing the mandate was essential to make the ACA’s ban on preexisting-condition exclusions work. Roberts rejected that too, reasoning that the clause allows Congress to support an existing exercise of power, not to create a new one from scratch.¹

Then came the move that saved the law. Roberts applied the constitutional avoidance doctrine, a longstanding practice of reading a statute in a way that keeps it constitutional where the language reasonably allows. The question was whether the shared responsibility payment could reasonably be read as a tax rather than a legal command to buy insurance.³ Three features pointed toward “tax”:

The amount was modest. As enacted, the payment phased in and topped out at the greater of $695 per adult or 2.5 percent of household income above the filing threshold, less than the cost of actual insurance.⁴
There were no criminal consequences. Going without insurance was not a crime and carried no jail time.
The IRS collected the payment as part of normal tax filing, and the statute barred the agency from using liens or levies. It could only offset the amount against a refund.⁵

Together, those features made the payment function like a tax on the choice to go uninsured, comparable to taxes on cigarettes or gasoline. Roberts, joined by Justices Ginsburg, Breyer, Sotomayor, and Kagan, upheld the mandate on that basis.¹

The Medicaid Expansion: Voluntary, Not Mandatory

The second constitutional fight involved money. The ACA extended Medicaid eligibility to all adults under 65 with incomes below 133 percent of the federal poverty level, effectively 138 percent with a built-in income disregard.⁶ Traditional Medicaid had covered mainly children, pregnant women, the elderly, and people with disabilities. The expansion brought in millions of low-income childless adults for the first time.

The federal government offered to cover 100 percent of costs for the newly eligible from 2014 through 2016, stepping down to 90 percent by 2020.⁷ The stick was much larger than the carrot. A state that refused to expand could lose all of its existing Medicaid funding, not just the new expansion money, but the funds it had received for decades to cover its traditional Medicaid population.

Medicaid runs between 15 and 30 percent of total state spending in most states. Seven justices found the threat of losing that funding unconstitutionally coercive, describing it as “a gun to the head.”³ Congress can offer states money to encourage new policies, but it cannot threaten to destroy an existing program to force compliance with a new one.⁸

The majority treated the expansion as different enough in scope and purpose from traditional Medicaid to count as a separate program. Congress could not hold the older program hostage to force states into the newer one. The remedy was narrow: states that declined would keep their existing Medicaid funding, and the expansion became voluntary.

The Dissents

Justices Scalia, Kennedy, Thomas, and Alito filed a joint dissent arguing the entire ACA should have fallen. They rejected the tax recharacterization, writing that Congress had labeled the payment a “penalty” and that reading it as a tax was revision rather than interpretation. They agreed the Commerce Clause could not support the mandate and that the Medicaid expansion was coercive, but they went further, arguing that both provisions were so central to the statute that the rest of the law could not survive without them. They compared the ACA to a Christmas tree whose ornaments become meaningless once the tree falls.

Justice Ginsburg concurred in the result on the mandate but disagreed with the Commerce Clause analysis and the Medicaid ruling. She called the activity-inactivity distinction a “newly minted constitutional doctrine” without basis in prior decisions. The uninsured, in her view, were active participants in the healthcare market who consumed billions in services and shifted the costs onto everyone else. She would have upheld the mandate directly under the Commerce Clause and upheld the Medicaid expansion’s enforcement mechanism as a permissible use of the spending power.

The Bottom Line

The Court’s ruling had three parts. The individual mandate survived under the taxing power, though not the Commerce Clause or the Necessary and Proper Clause. The Medicaid expansion itself was constitutional, but its enforcement mechanism was not. The unconstitutional portion was severable, so the rest of the ACA, including the insurance market reforms, subsidies, employer requirements, and consumer protections, stayed in force.¹

What the Ruling Means Today

The decision turned the Medicaid expansion from a federal requirement into a state-by-state choice. As of 2025, 40 states and the District of Columbia have adopted the expansion, and 10 have not. In non-expansion states, many low-income adults fall into a coverage gap, earning too much for traditional Medicaid but too little for marketplace subsidies.

The mandate’s story continued. The Tax Cuts and Jobs Act of 2017 reduced the shared responsibility payment to zero dollars for tax years beginning after December 2018.⁵ The mandate language stayed in the statute, so Americans are still technically required to maintain coverage, but there is no federal financial consequence for going without it.⁴

That zeroed-out penalty produced a follow-on lawsuit. In California v. Texas, a group of states argued that a mandate generating no revenue could no longer be justified as a tax, and that its unconstitutionality should take the rest of the ACA down with it. On June 17, 2021, the Supreme Court ruled 7–2 that the challengers lacked standing because they could not show any injury traceable to a mandate with no penalty, and it left the constitutional question unanswered.⁹

Several states have filled the enforcement vacuum with their own mandates. California, Massachusetts, New Jersey, Rhode Island, and the District of Columbia impose penalties on residents who go without qualifying coverage, generally calculated as the greater of a flat dollar amount per person or a percentage of household income. Vermont requires coverage by law but imposes no penalty for noncompliance. Residents of those jurisdictions still face financial consequences for lacking insurance, even though the federal penalty is gone.

1
Justia. National Federation of Independent Business v. Sebelius
2
Congress.gov. H.R.3590 – Patient Protection and Affordable Care Act
3
Legal Information Institute. National Federation of Independent Business v. Sebelius
4
Office of the Law Revision Counsel. 26 USC 5000A – Requirement to Maintain Minimum Essential Coverage
5
Internal Revenue Service. Questions and Answers on the Individual Shared Responsibility Provision
6
Medicaid and CHIP Payment and Access Commission. Medicaid Expansion to the New Adult Group
7
Medicaid and CHIP Payment and Access Commission. Federal Match Rate Exceptions
8
Congressional Research Service. Medicaid and Federal Grant Conditions After NFIB v. Sebelius
9
Supreme Court of the United States. California v. Texas, No. 19-840