One of the more interesting and potentially influential amicus briefs in United States v. Windsor, the case challenging DOMA Section 3, is one filed by a group of federalism scholars, all of whom have some connection to Cato and/or are generally sympathetic to the positions we take at the Center for Constitutional Studies. As Dale Carpenter puts it on the Volokh Conspiracy blog:
Today I’m proud to join three of my co-Conspirators — Jonathan Adler, Randy Barnett, and Ilya Somin — as well as Ernie Young and Lynn Baker in filing an amicus brief in United States v. Windsor arguing that DOMA Section 3 is unconstitutional. While this conclusion is shared by 69% of constitutional law professors around the country, our route to that end is probably not as widely shared.
Our view is that Section 3 fails equal protection review for a reason quite distinct from the standard approaches relying on heightened-scrutiny analysis. Whatever else may be its constitutional defects, Section 3 is not a constitutional exercise of any enumerated federal power. It is also not a “necessary and proper” measure to carry into execution any of Congress’s enumerated powers. Instead, it is an unprecedented expansion of federal authority into a domain traditionally controlled by the states. The federal government claims a hitherto unknown and sweeping power to determine marital and family status. While Congress has not (yet?) claimed a statutory authority to bar states from recognizing specific marriages, it has greatly complicated and burdened their police power to do so through the enforcement of DOMA. It may well be that Congress has authority to limit access to specific federal benefits otherwise available to validly married people. But Section 3, as an across-the-board enactment untethered to any specific power, is not plainly adapted to serve any “legitimate” interest of the federal government.
This may be an appealing argument for those on the Court who take federalism seriously and have a problem with Section 3 but may not be ready to extend the constitutional right to marry to same-sex couples. Coincidentally, the justice most likely to fall into that category is Anthony Kennedy—who will almost certainly be the swing vote in these cases—but the four "conservative" justices could also sign on to something like this even as they vehemently reject the broader constitutional argument in Hollingsworth v. Perry (the Prop 8 case) or in future cases challenging state denials of marriage licenses. The four "liberal" justices, meanwhile, don't care about limiting federal power through constitutional structure, but will presumably vote to strike down Section 3 on equal protection grounds.
Indeed, as I wrote in December, "I could see an opinion stating that marriage is an issue that our federal system leaves to the states and the federal government has to respect each state’s definition of it in granting benefits based on that status. That would mean that federal benefits would operate differently in different states, but so be it; gay married couples would have an incentive to live in the growing number of states that recognize their relationships."
This federalism argument may ultimately be too clever because the federal government certainly does have the power to define the terms in its statutes, which would collapse the issue in Windsor back to whether the restriction on DOMA's definition of marriage survives equal protection analysis (on which see Cato's brief). It would also probably be a mere way-station on the road to full marriage equality, becoming increasingly academic as more states allow same-sex marriage. But, as I said, it's more likely to resonate with certain members of the Court—and could have the potentially more important benefit of strengthening federalism in other areas of policy.
It would also mean the striking down of arguably the most signficiant federal law on federalism grounds in the modern era. We shall see.