The U.S. Supreme Court will hear oral arguments today, tomorrow, and Wednesday regarding the national health care reform law's constitutionality. The legal challenge to health care reform has focused on whether the federal government can mandate individuals to buy health insurance. But another argument is whether the federal government can require states to expand their Medicaid rolls.

Under health care reform, the federal government almost entirely subsidizes the cost of low-income residents in Illinois, and every other state, to enroll in Medicaid, beginning in 2014. As a condition of this federally paid for enrollment expansion, Illinois must pay 10 percent of enrollment costs starting in 2020. And the state mostly cannot reduce current eligibility levels.

Illinois' low-income, uninsured population should greatly benefit from national health care reform. But the state will keep close tabs on any tweak in the law that might alter current Medicaid obligations, given Springfield's political focus on Medicaid costs.