Final answer:
The U.S. Supreme Court ruled the ACA was partially constitutional, upholding the individual mandate as a tax, but ruling the government could not withhold Medicaid funds from states rejecting Medicare expansion.
Step-by-step explanation:
In 2012, the attorney general from 20 states filed a lawsuit alleging that the Affordable Care Act (ACA) was unconstitutional. The U.S. Supreme Court ruled that the ACA was partially constitutional. Specifically, they found that the individual mandate, which required citizens to purchase health insurance or pay a fine, could be considered a form of taxation within the power of the federal government.
However, they also ruled that the federal government could not withhold all Medicaid funding from states that refused to accept the expansion of Medicare under the ACA. Overall, the Supreme Court upheld the health care law as a constitutional extension of Congress's power to tax.