Sort of. He's saying that the constitution (including previous SCOTUS interpretation) doesn't specify what to do in the following case: Person is found guilty in a state court, person submits a petition of habeas corpus to a federal court, federal court doesn't find anything wrong with the original trial but decides that the person is actually innocent. The Antiterrorism and Effective Death Penalty Act of 1996 limits the power of federal judges to grant relief in cases to situations where the original state case broke federal law, or where the facts were clearly misapplied in the original case. Scalia seems to think there's nothing wrong with that limitation. Stevens disagrees, suggesting that there may be a real constitutional problem since that doesn't allow federal relief based on new evidence of innocence.