When Chief Justice John G. Roberts Jr. takes his usual center seat on the Supreme Court bench on March 26, he will begin presiding over an extraordinary three days of arguments that will determine the fate of President Obama’s sweeping health care law. The decision in the case, expected by June, will have practical consequences for tens of millions of Americans without health insurance, and it may affect Mr. Obama’s re-election chances.

No matter what you may think about the reforms from the Affordable Healthcare Act of 2010, the changes are already under way and they will continue on until they are required to be set in place in 2014. By that time, Americans will all be required to have some form of healthcare insurance coverage. However, there are still a large number of people in the country who are not yet fully aware of what the changes entail and how they – and their families – will be effected by them. The following are some of the more significant alterations to the healthcare system:

It took only a year to set up Medicare. But if President Barack Obama’s health care law survives Supreme Court scrutiny, it will be nearly a decade before all its major pieces are in place. And that means even if Obama is re-elected, he won’t be in office to oversee completion of his signature domestic policy accomplishment, assuming Republicans don’t succeed in repealing it.

Many small employers qualify for a small business health care tax credit under the federal health reform law — but they must file by the March 15 corporate tax filing deadline, according to the California Chamber of Commerce. The credit is intended to help small businesses and small tax-exempt organizations afford the cost of providing health benefits for their employees.

When Roron Chen went to a public clinic to try to see a doctor, she was put on the waiting list at the San Mateo Medical Center. A California state law requires counties to provide health care to people like Ms. Chen who cannot afford health insurance and have no other alternatives. Ms. Chen, a homemaker from San Mateo whose husband lost his job three years ago, had to wait nearly a year to see a doctor through the program. Like thousands of other uninsured people in San Mateo County, Ms. Chen waited and waited because the county did not have the money to subsidize her health care.

For all the debate about which Web sites have the best model for reliable reviews — paid or unpaid, anonymous or real name, Angie’s List or Yelp or TripAdvisor — one thing is certain: a robust ecosystem exists online for restaurant and hotel reviews that has changed those industries for the better. So it is puzzling that there is no such authoritative collection of reviews for physicians, the highest-stakes choice of service provider that most people make.

Mary Brown, whose case against the 2010 healthcare reform law is pending before the Supreme Court, argues that the government shouldn’t be able to force her to carry health insurance. Joined by three other individuals and a small-business trade association, she’s asking the justices to rule that the law’s insurance mandate is unconstitutional and that the rest of the act should be thrown out with it. But new revelations about her own situation make the case for the other side.