The Affordable Care Act (2010)

Signed by President Obama in March 2010, the Affordable Care Act expanded health insurance coverage to roughly twenty million Americans through subsidized exchanges, a Medicaid expansion, and new rules for the insurance market.

The Affordable Care Act, often called the ACA or Obamacare, was the most significant expansion of American health coverage since Medicare and Medicaid in 1965. It created online marketplaces where individuals without employer-sponsored coverage could buy regulated insurance plans, with premium subsidies on a sliding scale. It expanded Medicaid eligibility to adults earning up to 138 percent of the federal poverty line. It required insurers to cover people with preexisting conditions, capped out-of-pocket costs, and let young adults stay on their parents' plans until 26. It required most Americans to carry insurance through the individual mandate, enforced through a tax penalty. The law passed Congress in 2010 without a single Republican vote. It survived a constitutional challenge in 2012, when the Supreme Court in NFIB v. Sebelius upheld the individual mandate as a tax but allowed states to opt out of the Medicaid expansion. Roughly forty states have since accepted the expansion, with significant variation in coverage outcomes. The individual mandate penalty was zeroed out by the Tax Cuts and Jobs Act of 2017, though the rest of the law remained in force. The uninsured rate fell from roughly 16 percent in 2010 to under nine percent by the mid-2020s. The law has reshaped American healthcare without resolving the underlying argument over how it should be financed.