Some elements of the Affordable Care Act are already in effect:

>> Young adults up to age 26 are covered on their parents’ health plans.

>> Small businesses that cover employees are eligible for tax credits.

>> Lifetime limits on health coverage have been eliminated.

>> Insurance plans are available for people with pre-existing conditions.

Here are elements that have not yet been rolled out (most taking effect in 2014):

>> The individual mandate, requiring everyone to have insurance, whether through purchase, an employment benefit or a government source.

>> The Medicare Cost Review Board, which would review what care would be covered under Medicare.

>> Coverage for clinical trials of new treatments.

>> The elimination of annual limits to coverage.

>> The prohibition of refusal to enroll a patient with pre-existing conditions.

>> The expansion of Medicaid to about 30 million additional people.

On Monday, the U.S. Supreme Court begins three days of oral arguments on aspects of the challenge of the Affordable Care Act’s constitutionality.

Day 1: The court has allotted 90 minutes for arguments about whether the justices can even consider the challenge until key portions of the law go into effect. This could put the whole issue off for another two years.

Day 2: Justices will hear two hours of argument over the constitutionality of the individual mandate.

Day 3: The first 90 minutes will be spent hearing arguments on “severability.” This addresses the question: If the mandate or any other part is struck down, can that provision be severed, leaving the rest of the law intact?

The final hour of arguments concerns the constitutionality of compelling states to expand their Medicaid rolls.