The Supreme Court has finished the first of three days of arguments on the fate of the Obama administration's overhaul of the nation's health care system. The justices appear unlikely to allow an obscure tax law to derail the case.

In active questioning over 90 minutes on Monday, no justice appeared to embrace the view that the case has been brought prematurely because a law bars tax disputes from being heard in the courts before the taxes have been paid.

Under the new health care law, taxpayers who don't purchase insurance will have to pay a penalty on taxes due in 2015.

Solicitor General Donald Verrilli Jr., defending the health law, urged to court to decides what he called "the issues of great moment" at the heart of the case.