While oral arguments often are an uncertain guide to how the Supreme Court will vote, the Justices’ questions and comments during the second day of oral arguments about the Affordable Care Act signaled that the Supreme Court’s decision could be much closer than many had thought.

On behalf of various respondents, Paul Clement and Michael Carvin both argued that the Affordable Care Act exceeds Congress’ power under the Commerce Clause for two main reasons: (1) Congress has the power to regulate existing commerce, but not to force people to engage in commerce; and (2) the individual mandate is not a “necessary and proper” means of executing an otherwise constitutional exercise of Congress’ power to regulate commerce. Four justices seemed to agree, but four justices seemed to view the individual mandate's constitutionality differently.