For most of the uninsured, the ruling offers the promise of guaranteed coverage at affordable prices. Lower-income and many middle-class families will be eligible for subsidies to help pay premiums starting in 2014.
There's also an added safety net for all Americans, insured and uninsured. Starting in 2014, insurance companies will not be able to deny coverage for medical, nor can they charge more to people with health problems. Those protections, now standard in most big employer plans, will be available to all, including people who get laid off, or leave a corporate job to launch their own small business.
Seniors benefit from the law through better Medicare coverage for those with high prescription costs, and no copayments for preventive care. But hospitals, nursing homes, and many other service providers may struggle once the Medicare cuts used to finance the law really start to bite.
Illegal immigrants are not entitled to the new insurance coverage under the law, and will remain one of the biggest groups uninsured.
Obama's law is by no means the last word on health care.
Experts expect costs to keep rising, meaning that lawmakers will have to revisit the thorny issue perhaps as early as next year, when federal budget woes will force them to confront painful options for Medicare and Medicaid, the giant federal programs that cover seniors, the disabled, and low-income people.
Even some supporters of the law candidly admit it's only a first installment: get most people covered, and then deal with the problem of costs.
The health insurance's industry top lobbyist said the ruling relieved one big concern for insurers — that the mandate would be struck down, allowing people to literally buy coverage on the way to the hospital. But the companies are still worried about costs.
"Without universal participation you have no incentive to purchase coverage until you are sick, and that is not an insurance system," said Karen Ignagni, president of America's Health Insurance Plans. "Now it's time to turn all the attention toward affordability." The industry continues to fight taxes and other requirements in the law.
In contrast to the states, the vast health care industry is better prepared. When the law passed in 2010, insurers, hospitals and major employers immediately started planning to carry it out. Many of the changes called for in the law were already being demanded by employers trying to get better value for their private health insurance dollars.
"The main driver here is financial," said Dr. Toby Cosgrove, CEO of the Cleveland Clinic, which has pioneered some of the changes. "The factors driving health care reform are not new, and they are not going to go away."
- Photo gallery: Christmas around the world
- NORAD 'tracks' Santa's journey across globe
- Officer kills armed 18-year-old near Ferguson
- Our six heroes of 2014
- Ex-President George H.W. Bush to stay...
- Final goodbye: A roll call of some who died...
- Blizzard gives Hawaii summits a White Christmas
- CDC monitoring laboratory technician for...
- NYPD: Cop ambush killer told passers-by... 15
- Going it alone, Obama rocked the boat... 13
- Officer kills armed 18-year-old near... 10
- Pope in blistering critique of Vatican... 9
- Key developments in the case of slain... 9
- Killings of 2 New York officers trigger... 6
- Senate, CIA agree torture program was... 6
- Sony announces limited release for 'The... 5