The idea that lawsuits challenging the law could be blocked was held by several lower federal court judges and was assigned to Washington, D.C., lawyer Robert Long to defend Monday. It is premised on the belief that the 1867 law known as the Anti-Injunction Act forbids lawsuits against federal tax policies until after someone has actually paid the tax. 

But from the outset of Monday's arguments it was clear the justices weren't too sympathetic to that view because of the language Congress eventually used in crafting the law. The Affordable Care Act says the cost for not complying with the requirement to obtain health insurance is a penalty -- not a tax. 

"Congress has nowhere used the word 'tax,'" Justice Stephen Breyer said to Long. "What it says is penalty." 

Breyer was hardly the only justice to suggest the designated penalty isn't a tax.