Amen, Chris. Someone asked me this same question about the proposed federal marriage amendment recently, and I had to respond, no, a constitutional amendment cannot be found unconstitutional, because it is by definition constitutional. I can sort of understand the confusion, though; after all, as a legal document, the Constitution should be internally consistent, right? And it could be argued that a federal marriage amendment would clash with the Equal Protection Clause of the Fourteenth Amendment (at least under the modern interpretation of that clause). What better body to resolve such internal inconsistencies than the U.S. Supreme Court?

But it doesn’t work that way. Or at least it hasn’t. As stated 200 years ago in Marbury v. Madison, the Supreme Court’s role is to judge whether a state or federal law violates the Constitution. A constitutional amendment is higher than an ordinary law. The entire point of it is that it becomes part of the Constitution. If a federal marriage amendment gets ratified, any state or federal law that allows gay marriage will be as unconstitutional as a law that violates free speech or the free exercise of religion.

Of course, if the entire Supreme Court wanted to, it could probably create an entirely new form of judicial review that would allow it to declare part of the Constitution unconstitutional. After all, Marbury v. Madison itself was written by Chief Justice John Marshall. We’re not talking about God’s laws here; we’re talking about people.

There’s only one example I can think of in which the Supreme Court has effectively invalidated part of the Constitution: the Slaughterhouse Cases of 1873, in which the Supreme Court basically read the Fourteenth Amendment’s Privileges and Immunities Clause out of the Constitution five years after the amendment had been ratified. (I don’t know too much about the Slaughterhouse Cases, but I know the result.)

That said, although a federal marriage amendment is a scary idea, I don’t think it has a good chance of being ratified. For a constitutional amendment to be ratified, first two-thirds of the Senate and two-thirds of the House must pass it; in other words, the Republicans need a bunch of Democrats on their side. Second, it must be passed by both legislatures in three-fourths of the states. That’s 38 states (since there’s no such thing as 37.5 states). In other words, if one legislature in each of 13 states votes against it or doesn’t vote on it, it doesn’t get ratified. Amendments are notoriously hard to pass; that’s why there’s no anti-flag-burning amendment today. And look at the story of the Equal Rights Amendment.

This piece has a good explanation of why a federal marriage amendment probably won’t get ratified. (The writer opposes gay marriage, though.) The amendment process was designed to be difficult; constitutional change is not supposed to be subject to the passions of the moment. It’s supposed to require broad consensus among the American people. And fifty-five percent is not a consensus. Granted, given the speed at which information travels these days, anything can happen. And how many unthinkable things have happened in the last few years? A presidential impeachment; a tied presidential election; 9/11.

Nothing is impossible anymore.