The U.S. Supreme Court is scheduled to hear arguments from a coalition of states that forcing people to buy health insurance oversteps the powers of Congress and is unconstitutional. And, many Republicans would repeal the entire Affordable Care Act if they had a chance. We can't tell yet where the justices will come out, but Bob Christenson would give them an earful if he could.

Let's look at the numbers. Christenson is a partner and benefits attorney in Fisher & Phillips' Atlanta, Georgia, office. And, he says, recent research makes it clear that scuttling the individual mandate would be disastrous.

Here are the statistics, and we hope they give you as much pause as they did us: According to the federal Agency for Healthcare and Quality, just 5% of the civilian population accounted for nearly 50% of healthcare expenditures in 2008 and 2009. Worse still, only 1% of the population accounted for about 21% of healthcare expenses.

We strongly suspect that 1% are the very elderly, who are nearing the end of life. And, the figures lead us that way: People over 45 are disproportionately represented among the top spenders—and we all know that the United States is a graying nation. Furthermore, although people over 65 represent only 13.2% of the population, they account for 42.9% of individuals in the top 10% of healthcare spenders. That's why healthcare coverage for retirees is such a huge expense for employers that must provide it.

What's the worst that could happen? A second study that caught Christenson's interest came from the Robert Wood Johnson Foundation and the Urban Institute. This report predicts that, should the individual mandate be declared unconstitutional, dire consequences will follow. Younger and healthier individuals will be much more likely than older, less healthy people to forgo healthcare insurance—leaving health plans and insurers to bear much higher costs of covering those older people.

The Johnson Foundation/Urban Institute study identifies the impact: The current estimated total of 26 million uninsured people would rise to 42 million. The majority of people who get their coverage from the insurance exchanges that will be in place by 2014 are likely to be over 45—precisely the group that generates the most healthcare expenditures. And, premium costs in those exchanges could rise by 25%.

With many employers now considering replacing their own health plans by buying coverage for employees from the exchanges, the consequences of price increases that big could be disastrous.

Administration rides the fence. Late in January, as the individual mandate challenge faced the high court, the White House announced that the Affordable Care Act could survive without the mandate. Maintaining that the Commerce Clause of the Constitution gives the government the authority to impose the mandate, the administration nevertheless said that most of the other provisions of the law would be unaffected by the elimination of the mandate, and many provisions will have been in effect for several years by 2014.

The National Federation of Independent Business, which opposes the mandate, says, by contrast, that it is so essential to the law that the entire law should be scrapped if the mandate is invalidated. The administration countered that striking down one provision of any law would not justify throwing out the whole thing. But it conceded that the "guaranteed issue" and "community rating" provisions—which would prevent insurers from denying coverage or charging higher premiums based on an individual's medical or family history—must also be stricken if the individual mandate is.

Wellness programs are key to U.S. healthcare. Christenson acknowledges that even if the individual mandate survives, it is unlikely that the Affordable Care Act will lead to substantial reductions in healthcare costs. Employers should embrace wellness programs based on their employees' habits and lifestyles; such programs can be effective in reducing costs. They permit limited penalties or rewards for people who focus on such changes as smoking cessation or weight loss. Another good tool, he says, is consumer-driven healthcare.