National Federation of Independent Business v. Sebelius, 567 U.S. 519 (2012), is a landmark United States Supreme Court decision in which the Court upheld Congress's power to enact most provisions of the Patient Protection and Affordable Care Act (ACA), commonly called Obamacare, and the Health Care and Education Reconciliation Act (HCERA), including a requirement for most Americans to pay a penalty for forgoing health insurance by 2014. The Acts represented a major set of changes to the American health care system that had been the subject of highly contentious debate, largely divided on political party lines.

The Affordable Care Act (ACA), formally known as the Patient Protection and Affordable Care Act (PPACA) and colloquially as Obamacare, is a landmark U.S. federal statute enacted by the 111th United States Congress and signed into law by President Barack Obama on March 23, 2010. Together with the Health Care and Education Reconciliation Act of 2010 amendment, it represents the U.S. healthcare system's most significant regulatory overhaul and expansion of coverage since the enactment of Medicare and Medicaid in 1965.