The largest association of U.S. physicians praised the Supreme Court's decision Thursday to uphold the Affordable Care Act as a key to expanding health care to some 30 million Americans.

In a 5-4 vote, Chief Justice John Roberts -- a conservative appointed by President George W. Bush --  joined the court's liberal judges to rule the Affordable Care Act's individual mandate requiring most Americans to purchase health insurance is in fact constitutional. The Justices ultimately ruled that while the mandate, demonized for years by opponents as an example of government overreach, violates the Commerce Clause of the U.S. Constitution. However, five Justices agreed that the penalty someone must pay if he or she refuses to buy insurance is a kind of tax that Congress can impose using its taxing power.

While a majority of the court ruled the law's Medicaid expansion is constitutional, it simultaneously said it is illegal for the federal government to withhold Medicaid funds to states for non-compliance with the reform law's expansion provisions.

The AMA praised the decision, saying it will spur innovation, simplify administration and expand coverage.

This decision protects important improvements, such as ending coverage denials due to pre-existing conditions and lifetime caps on insurance, and allowing the 2.5 million young adults up to age 26 who gained coverage under the law to stay on their parents' health insurance policies, the AMA said in a statement. 

The expanded health care coverage upheld by the Supreme Court will allow patients to see their doctors earlier rather than waiting for treatment until they are sicker and care is more expensive. The decision upholds funding for important research on the effectiveness of drugs and treatments and protects expanded coverage for prevention and wellness care, which has already benefited about 54 million Americans. 

The health reform law upheld by the Supreme Court simplifies administrative burdens, including streamlining insurance claims, so physicians and their staff can spend more time with patients and less time on paperwork. It protects those in the Medicare 'donut hole,' including the 5.1 million Medicare patients who saved significantly on prescription drugs in 2010 and 2011. These important changes have been made while maintaining our American system with both private and public insurers.