DISPUTES: Residents debate the Affordable Care Act outside of the Supreme Court in Washington D.C., capital of the United States, on March 28, the last day of hearings on the medical reform bill (FANG ZHE)

When David Zoltan lost his job and health insurance during the recession, the 34-year-old Chicago resident planned to simply buy a new policy – until the insurance companies denied him coverage based on a pre-existing condition of Diabetes. Forced into hospital emergency rooms when he ran out of Insulin, Zoltan joined the ranks of the estimated 50 million uninsured Americans, who live one major illness or accident away from financial ruin.

Then, two years ago, Zoltan caught a break. As part of the 2010 Affordable Care Act, the federal government allocated $196 million for the state of Illinois to start a new health insurance program for people with pre-existing conditions. Zoltan was one of the first to sign up for the program. He now pays about $1,848 a year in premiums, and must pay $2,000 out of pocket before coverage starts.

"As a diabetic, I never again want to be without health insurance," Zoltan told the Associated Press. "Anything is better than not having coverage at all."

A new study released by the Department of Health and Human Services shows that as many as 129 million Americans under the age 65 have a pre-existing health condition, like Zoltan, and would be at risk of losing their health insurance if the U.S. Supreme Court strikes down key provisions of the Affordable Care Act – called "Obamacare" by its critics. Arguments on the new law began March 26, and the chief justices are expected to make a ruling in June.

The law expands the government's existing Medicare and Medicaid programs, establishes state insurance exchanges for individuals to purchase affordable plans, allows young adults to be covered under their parents' policies until age 26 and requires insurance companies to offer policies without regard to pre-existing conditions. To pay for the expanded coverage, the government has enacted a handful of tax increases, offsets and required all uninsured Americans to purchase coverage by 2014 or pay a penalty. It is the latter requirement, known as the "individual mandate," that has become the focus of the legal battle and threatens the entire existence of Obamacare. Is it legal for the government to tell citizens they must purchase health insurance?

"The idea that was raised was that if the government can require people to purchase health insurance on the private market," said Dr. Daniel Ehlke, assistant professor of the Department of Health Policy and Management at the School of Public Health at SUNY Downstate in Brooklyn, NY, "then what's to stop the government from requiring the purchase of anything else on the private market?"

The Obama administration defends the mandate, saying the government has the right to regulate interstate commerce. The law's challengers – 26 states led by Florida, the National Federation of Independent Business and several individuals – argue that Congress exceeded its constitutional authority and that the mandate infringes on individual liberty and state rights.

If the government can force you to buy health insurance, said Ehlke, then, conceivably, it could force you to purchase other goods it deems essential for your health and safety, such as a cell phone or broccoli. The four conservative chief justices on the court aimed a barrage of questions at the government's chief solicitor on this point – leading to speculation that the individual mandate component would be struck down by the courts.

"Many would argue that when it comes to the individual mandate, there's not a lot of precedent there. Some people point out the United States requires individuals to purchase car insurance. However, one of the counterarguments is that driving is a privilege, whereas health care is something that everyone will have to receive at some point. There's no choice on whether to participate in that market," Ehlke said.

Two justices have suggested that if the Court finds the mandate illegal, it should invalidate the whole act instead of picking apart the law's provisions. The comments set off a flurry of speculation in the media that Obamacare was "dead on arrival."

"It's a question of severability, whether you can cut a certain portion of the act and the rest of it stands, or whether the entire edifice falls," Ehlke said.

Despite the political rhetoric and the media speculation, Ehlke cautioned that there may be more flexibility in the new law then the government states. The Obama administration had previously argued that the Affordable Care Act is not easily severable, hoping the court would be less likely to strike down part of the law if the survival of the act was at stake. Now, the administration seems to be softening its stance, Ehlke said.

"When it became clear that the individual mandate might be at risk, the government said maybe some parts of the act related to the mandate might be severed. There were a lot of revisions following arguments related to severability and we really don't know on that procedural point how the court is going to rule," he said.

Playing Politics

The battle over the individual mandate has been divided starkly over political party lines, with Democrats generally supporting the mandate and Republicans arguing that the government has overstepped its bounds. However, for two decades, Republicans have widely supported the idea of an individual mandate for health insurance. It was the alternative to the government-run single payer system proposed by the late Democratic Senator Edward M. Kennedy and to the employer mandate proposed by President Bill Clinton in 1993, according to Bloomberg News. It was only after the mandate became a key component of Obamacare that Republicans took an opposing stance.

"What we are seeing now is baffling,'' Senator Charles Schumer of New York, the No. 3 Senate Democrat, told The New York Times. "Republicans have gone from being the main champions of the individual mandate to being its main antagonist.''

On the other hand, President Obama criticized the individual mandate during his 2008 campaign for the presidency, and accepted it only as a compromise to his push for a single-payer system run directly by the government. Even supporters of the new law have criticized the administration for fumbling the rollout of health care reform, saying that Obama failed to clearly explain the benefits to the public.

The American public seems confused. Polls show that only about one-third of voters support the individual mandate but about two-thirds back the provision that prohibits insurance companies from discriminating against people with pre-existing conditions, according to Bloomberg News. Voters do not seem to realize that the two provisions are inextricably linked – if there is no mandate, then likely there will be no coverage for pre-existing conditions. In a recent poll by The New York Times, 48 percent of respondents called Obamacare "confusing" and 38 percent said the law should be overturned.

Republicans have pounced on Obamacare as an election-year issue popular with voters. Senate Republican leader, Mitch McConnell of Kentucky, said: "Regardless of how the Supreme Court rules on the constitutionality of what I believe is the single worst piece of legislation passed in the time I've been in Congress, it's still a bad idea. If the Senate Republicans become the majority next year, the first item on the agenda will be the repeal of Obamacare and the replacement of it with something that makes more sense and is targeted at the problems we actually have in American health care.''

The Supreme Court will decide if Republicans get their wish to repeal Obamacare, and Ehlke warned against reading too deep into their deliberations. The court is acutely sensitive to public opinion, and does not want to be seen as overreaching. Now, Ehlke said, Americans begin the "waiting game" until the ruling is issued in late June.

"We simply do not know how the court is going to rule on the individual mandate, or on any of the other points of the Affordable Care Act," Ehlke said.

For David Zoltan, the only option is to stand on the sidelines and watch the debate. He has found work, but the job doesn't include health benefits, he told the Associated Press, so he'll stay on the federally funded health plan. The individual mandate is needed, he said, to spread the risk among the well and the sick, and keep insurance affordable.

(Reporting from New York City)