That law is also why debates about whether illegal immigrants would get health coverage under the law are spurious. Yes, they will. They get coverage now. It's a matter of whether they get coverage through an insurance program or through emergency rooms, as they do now.

"We are a compassionate society," Desser said. "We have already decided that we don't want people dying on the street when they can't afford care."

COVERAGE CHANGES

Whenever there's a mandate to buy coverage, the government also has to spell out what type of coverage meets that mandate. In other words, it has to create a model insurance policy that meets the requirements in the law.

Current proposals provide only a few details of what would be in these standard policies. Here's what we know so far:

-- All policies would provide hospital, physician and preventive care.

-- Young people would be able to buy a bare-bones policy called the "young and invincible" plan. It would have high deductibles and low premiums but would cover major medical.

-- The amount you have to pay for such things as co-payments and deductibles would be capped. Under current proposals, the most a family would have to spend would be about $11,900 annually. After that, all costs would be covered, regardless of the restrictions in your plan. (Individual caps are half as much.)

-- Consumers would be able to choose from a group of standardized policies, some of which would offer lower premiums but higher deductibles. Other policies would offer high-end coverage but at a higher monthly cost.

-- Subsidies would be provided to people who could not afford insurance premiums or the cost of their deductibles and co-insurance. Currently, those subsidies would kick in for anyone with income below 300 percent of the federal poverty guidelines. These guidelines vary based on family size and location. A family of four living in the continental U.S. would get the subsidy up to about $66,000 in income, Dresser said.

The most contentious coverage debate boils down to this: Congress doesn't want to be accused of approving skimpy coverage. But the more it mandates in the model policies, the more you pay. If you demand that people buy insurance, you don't want to price them out of the market.

"There is a big balancing act going on between the cost of the legislation and the adequacy of the subsidies and the coverage itself," Altman said. "A lot of this is going to be tweaked several times as this goes through the process."