If a Democrat is elected president in 2008, he or she will face a significant and not-yet-discussed problem: Bush and Reagan appointees to the federal courts of appeals. I'm speaking not of the high-profile constitutional cases (which are few and far between), but of the less publicized but more regular work of any administration, involving (for example) environmental policy, occupational safety and health policy, energy policy, communications policy, and labor law.

Thomas Miles, a lawyer-economist at the University of Chicago, and I have been working for several years on a large project of tabulating and assessing the voting behavior of court of appeals judges in regulatory cases. We're not ready to release our findings (forthcoming in the University of Chicago Law Review) or to discuss them in any detail, but here's one significant conclusion: Republican appointees to the lower courts are far more likely to invalidate, as "arbitrary," liberal decisions than conservative decisions. This tendency is especially pronounced when Republican appointees sit on RRR panels, that is, on panels without any Democratic appointees.

It follows that if a Clinton or Obama administration issues a number of environmental regulations that are plausibly characterized as liberal, it will sometimes have an uphill battle in court -- and much of the time, its regulations will be struck down.

--Cass Sunstein