A"tell" in poker is a subtle but detectable change in a player's behavior or demeanor that reveals clues about the player's assessment of his hand. Something similar has happened with regard to the insurance mandate at the core of last month's health reform legislation. Congress justified its authority to enact the mandate on the grounds that it is a regulation of commerce. But as this justification came under heavy constitutional fire, the mandate's defenders changed the argument—now claiming constitutional authority under Congress's power to tax.
This switch in constitutional theories is a tell: Defenders of the bill lack confidence in their commerce power theory. The switch also comes too late. When the mandate's constitutionality comes up for review as part of the state attorneys general lawsuit, the Supreme Court will not consider the penalty enforcing the mandate to be a tax because, in the provision that actually defines and imposes the mandate and penalty, Congress did not call it a tax and did not treat it as a tax.