American College of Physicians officials are offering a salute and a sigh of relief in reaction to the recent Supreme Court ruling that upholds the legal backbone of the Affordable Care Act.

The Supreme Court ruled 5-4 that Congress can impose a penalty on citizens who do not purchase health insurance, a provision of the law widely known as the individual mandate.

"Had the court overturned the entire law or major elements of the law, it would have introduced a chaotic situation to many of our members," said Bob Doherty, ACP's senior vice president for governmental affairs and public policy. "A lot of things would have been undermined or overturned."

In an opinion written by Chief Justice John G. Roberts Jr., the court upheld the individual mandate as constitutional under Congress's authority to tax citizens. That had been one of the Obama administration's backup arguments in support of the mandate. The administration's principal argument -- namely that Congress had the authority to require such a mandate because of its powers to regulate interstate commerce -- was rejected by the court.

Some observers have expressed concern that the ruling weakens the so-called Commerce Clause of the Constitution and could lead to new legal challenges to Social Security, Medicare and Medicaid.

But ACP's president, Dr. David L. Bronson, praised Roberts' opinion as a "brilliant" way to make a point about the Commerce Clause while still upholding a law that will provide health coverage to tens of millions of uninsured people.

"In the end, it ended up with a majority in favor of 98 percent of the current provisions of the act," Bronson said.

The ruling did not completely clear the road for implementation of the Affordable Care Act, however. The Supreme Court held that states could refuse without penalty billions of dollars in federal aid to expand their Medicaid programs, a part of the law that would extend health coverage to millions of poor or disabled people.

Before the ruling, the Affordable Care Act held that states that refused to use the federal money to expand Medicaid could lose all their Medicaid funding.

"The ACA would have used carrots and sticks to get states to cover people up to 133 percent of the poverty limit," Doherty said. "The Supreme Court has said you can keep giving them carrots, but you can't use the stick to beat states into submission."

The governors of six states have gone on record saying they will refuse federal money to expand Medicaid, and several others are leaning in that direction, according to The Washington Post. The federal government hopes to sway those opposed as well as the states still undecided by the time the expansion begins in 2014.

A widespread rejection of Medicaid expansion could further deepen the economic divide between the haves and have-nots in the United States, Doherty explained. Other parts of the health care law provide for middle-class and upper-class health coverage through state-level insurance exchanges, while leaving affordable insurance beyond the reach of the needy.

"You would have a situation where the poorest of the poor might have no access to health care coverage in some states, while people with higher income do," he said. "The worst thing you can do is set up a system where the poor are left out."

Bronson and Doherty both said they doubted that recalcitrant states would hold out for long, noting that many states initially refused to participate in Medicaid when the program was enacted in 1965. Today, all states accept federal dollars for their own Medicaid programs.

"My personal opinion is it will be very hard to resist the amount of assistance that's available," Bronson said. "The pressure at the state level will be enormous. There will be a few states that will hold out, but they will eventually come around."

Hospitals and physicians will be at the forefront of that pressure, Doherty said, because they now have to eat the cost of treating uninsured people who come in for expensive last-minute emergency care.

"We're going to recommend that ACP chapters lobby their governors and legislators to accept the federal dollars so the most vulnerable will have access to health care," he said. Consumer groups also are expected to lobby states to extend coverage to the poor.

"At this point, the action really is moving to the state level," Doherty said. "In most states, it's not a unilateral decision the governors can make on their own. Legislators have a say, and constituents have a say. They might be convinced it's in their state's best interest to accept the money and expand Medicaid."

Politicians might also find that the public has little taste for a continued fight over health care reform.

An early reaction poll by the Kaiser Family Foundation found that a majority of Americans -- 56 percent -- would like to see opponents stop their efforts to block implementation of health care reform and move on to other major national problems. Four out of five Democrats said opponents should move on, along with half of independents and a quarter of Republicans.

Nonetheless, health reform will probably maintain its high profile as the 2012 presidential and congressional races heat up.

Presumptive Republican presidential nominee Mitt Romney decried the Supreme Court's ruling as soon as it became public and said he will continue to oppose health reform.

"What the court did not do on its last day in session I will do on my first day if elected president of the United States," Romney said. "I will act to repeal Obamacare."

If the public's distaste for continued warfare over health care reform is reflected at the ballot box in the fall, it could smooth the path for implementation of the law. On the other hand, if opponents of the Affordable Care Act win election to key positions, then battles over the act could grind on for years.

"The 2012 elections will be decisive, one way or the other, in determining the law's future," Doherty said.