Critics might have found a loophole in the health care law worth challenging—the insurance exchanges. Beginning 2014, Americans can get subsidies to help pay for insurance purchased through exchanges. The issue is whether the subsidies will be available in exchanges set up and run by the federal government in states that fail or refuse to establish their own exchanges. Supporters say Congress may have made a drafting error, but that its intent is clear: subsidies should be available in federal and state exchanges. “There is no coherent policy reason why Congress would have refused premium tax credits to the citizens of the states that end up with a federal exchange,” said Timothy S. Jost, a health law expert at Washington and Lee University. The Obama administration issued a rule that allows tax credits for insurance bought in either a state or a federal exchange.