What does the ruling mean to me?
The Supreme Court decision upholding President Barack Obama's health care law affects nearly every American. The law tells almost everyone they must have health coverage and guarantees it will be available to them even if they are already ill or need hugely expensive care. It helps the poor and many middle-class people afford coverage.
What the justices said
The high court upheld almost all of the law, including the most disputed part: the mandate that virtually all Americans have health insurance or pay a fine. The court said that fine is essentially a tax, and that's why the government has the power to impose it.
The ruling limited the law's plan to expand the Medicaid insurance program for the poor, a joint effort of the federal government and states. It says the U.S. government cannot withhold a state's entire Medicaid allotment if it doesn't participate in the expansion.
Chief Justice John Roberts sided with the court's four liberal justices — Stephen Breyer, Ruth Bader Ginsburg, Elena Kagan and Sonia Sotomayor — to form the 5-4 majority.
Huge political impact
The court upheld Obama's signature legislative achievement. Final word from the court amplifies the most polarizing issue of his re-election campaign against Republican Mitt Romney.
GOP lawmakers and Romney have promised to repeal the law if they are in power after the November election.
The 2010 health care law will keep taking effect. It's expected to bring coverage to about 30 million uninsured people. Overall, more than 9 in 10 eligible Americans will be covered.
Some parts are already in effect: Young adults can stay on their parents' insurance up to age 26. Insurers can't deny coverage to children with health problems. Limits on how much policies will pay out to each person over a lifetime are eliminated. Hundreds of older people already are saving money through improved Medicare prescription benefits. And co-payments for preventive care for all ages have been eliminated.
Starting in 2014, almost everyone will be required to be insured or pay a fine. There are subsidies to help people who can't afford coverage. Most employers will face fines if they don't offer coverage for their workers. Newly created insurance markets will make it easier for individuals and small businesses to buy affordable coverage. And Medicaid will be expanded to cover more low-income people.
Insurers will be prohibited from denying coverage to people with medical problems or charging those people more. They won't be able to charge women more, either. During the transition to 2014, a special program for people with pre-existing health problems helps these people get coverage.
An assortment of tax increases, health industry fees and Medicare cuts will help pay for the changes.
Still, not everyone will be covered
An estimated 26 million people will remain without coverage once the law is fully implemented, including illegal immigrants, people who don't sign up and choose to face the fines instead, and those who can't afford it even with the subsidies. That number could be higher, depending on whether any states refuse the Medicaid expansion.
The taxing truth
When the law was before Congress, Obama and Democrats avoided calling its penalty for going uninsured a "tax." But the administration argued before the Supreme Court that the law was constitutional as a federal tax. The court rejected two other Obama administration arguments for the law but accepted the tax one.
In 2016, after the law is fully in place, about 4 million people will pay the penalty to the Internal Revenue Service for being uninsured, the Congressional Budget Office has estimated. They would pay $695 per uninsured adult or 2.5 percent of family income, up to $12,500 per year.
The IRS can't prosecute violators or place liens against them, however. Its only enforcement option may be withholding money from refunds.
What are Republicans saying?
"Obamacare was bad law yesterday. It's bad law today," Romney said after the ruling.
The Republican-led House already has voted for repeal but can't push it forward so long as Obama's in the White House and Democrats lead the Senate — making the November elections crucial.
Senate Republican Leader Mitch McConnell called the court decision "a fresh start on the road to repeal."
Obama says the decision upholds the fundamental principle that in the wealthiest nation on earth, no one should be ruined financially by an illness or accident.
He called it "a victory for people all over this country whose lives will be more secure because of this law."
About that mandate
Many parts of the law have proven popular. But the insurance mandate is widely disliked.
Each time AP has asked in polls, more than 8 in 10 Americans have said the government should not have the right to require everyone to buy health insurance.
The public also has tilted against the law as a whole over the two years since it was passed. About half opposed it and a third were in favor in an AP-GfK poll shortly before the Supreme Court ruled.