 Well, how are lower courts supposed to handle that? Forty years ago, the Supreme Court gave them a rule in a case called Chevron v. Natural Resources Defense Council, and the rule was this. If it is an ambiguous part of the law and the agency which is supposed to enforce the law has a reasonable interpretation of it, the lower court should defer to that interpretation, even if it might reach a different conclusion on its own. And that was known as Chevron deference.