Despite the best efforts of the American political class (aka “the perpetual party in power”), the US Constitution limits Congress to a specific list of powers found in Article I, Section 8. In other words, if it is not in this list the Federal Government can’t do it. These are the Enumerated Powers of Congress.
Read that list carefully; look for the word “marriage”.
It isn’t in there.
Now I’m certain someone will make the case that the Interstate Commerce Clause (“To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes”) grants such power—thereby reducing the institution of marriage to a pure commercial transaction.
While the Interstate Commerce Clause traditionally is invoked by the political left to do pretty much any damn fool thing they want to, conservatives have certainly gone down such anti-constitutional paths before. After all, most conservatives see nothing wrong with the proposition that the Interstate Commerce Clause gives the Federal Government the power to send people to prison for growing marijuana in their own back yards.
But if the Federal Government doesn’t have the power to define and regulate marriage, who does? The Tenth Amendment answers that question, establishing that “[t]he powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.”
So that leaves us at the Dick Cheney position: “It’s up to the States.”
Well, not quite. Note the Tenth Amendment says that the powers not granted to the Federal Government “are reserved to the States respectively, or to the people.” In other words, not every possible governmental power can be freely exercised by the States. Some are ultimately held by the people themselves. (Note that everywhere in the Bill of Rights where the term “the people” is used, it is used in the sense of the rights of individual citizens, not as some sort of fuzzy collective right.) The Ninth Amendment confirms this view, stating “[t]he enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.”
Marriage has both civil and religious dimensions; and it is the religious aspect of marriage that the people arguing most forcefully against the legality of gay marriage tend hold to most dearly. But the First Amendment to the Constitution is quite clear on the government’s role in religious matters: “[c]ongress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof”. Since under the Fourteenth Amendment, that applies to the States as well as the Federal Government, the States should not have the power to define or regulate marriage either. Such a “hands off” approach is not without precedent. That’s very much the way that the Federal and State governments treat churches themselves.
Constitutionally, the definition of marriage must be left to the people individually and to the myriad of religious institutions separately.