摘要：Intuition suggests that preemption is a constitutional issue-when we ask whether a state law has been nullified because it conflicts with a federal law, we seem to be asking a constitutional question. But to an outsider, some of our commentary and practice would suggest that preemption has little to do with the Constitution at all. Professor Meltzer, for example, calls preemption a "subconstitutional" issue, and Professor Hoke urges that preemption be "de-constitutionalized." The Supreme Court treats preemption as a constitutional issue at one moment and as a statutory issue the next. Unlike other constitutional issues, some courts hold that preemption issues categorically do not warrant Pullman abstention. The rule that courts should avoid deciding constitutional questions whenever possible is not uniformly applied to preemption issues—in fact, courts often decide preemption questions in order to avoid other constitutional issues. Historically, suits to enjoin enforcement of allegedly preempted state laws did not qualify under the federal statute providing a special panel of three district court judges for suits to enjoin enforcement of state law on federal constitutional grounds.
