"This decision is at odds with decades of established Supreme Court law which has consistently found that courts have a constitutional obligation to preserve as much of the statute as can be preserved," he said. He said he does not believe this decision will be upheld.

Durbin also said Article 1, Section 8 of the Constitution can be read in a way that allows the insurance mandate, and said tomorrow's hearing would focus on this language. Durbin argued that the health insurance industry is properly seen as "commerce" that can be regulated, and said the insurance mandate is needed in order to eliminate discrimination against people with pre-existing conditions.

"You cannot eliminate exclusions on pre-existing conditions, and not move more and more people into the risk pool at an earlier stage," he said. Without the mandate, he said, people would move into the insurance pool only when they are sick, and this would destroy the insurance industry's risk model.

Durbin said he believes the tax imposed for not buying insurance and the mandate itself will be seen as "necessary and proper" rules that help the United States end discrimination against people with pre-existing conditions. This is a reference to clause 18 of Article 1, Section 8, which says Congress has the power to make laws "necessary and proper" to exercising its authority.

Opponents have argued that by requiring the purchase of health insurance, the law goes too far in its regulation of commerce, because it is the first time Congress has required individuals to engage in commerce. Those arguments persuaded Vinson and Judge Henry Hudson in Virginia to rule against the law. An equal number of judges have ruled in favor of the law, and most expect the Supreme Court to ultimately rule on its constitutionality.