The U.S. Supreme Court has upheld the Affordable Care Act, President Obama’s signature healthcare reform bill. Chief Justice John Roberts proved to be the surprise deciding vote, joining with the court’s four liberal members. Citing the authority of Congress to impose taxes, the decision affirms the law’s individual mandate provision that requires Americans who can afford it to either obtain health insurance or pay a penalty by 2014. Shortly after the ruling came down, President Obama said the Supreme Court had ended the long-running debate over his healthcare law.

President Obama: “The highest court in the land has now spoken. We will continue to implement this law. And we’ll work together to improve on it where we can. But what we won’t do, what the country can’t afford to do, is refight the political battles of two years ago or go back to the way things were.”

Although the law remains mostly intact, the court ruled against a provision that allows the federal government to withhold Medicaid funding from states that do not comply with the program’s expansion.