The proposed "Federal Marriage Amendment" was introduced by Rep. Marilyn Musgrave (R. CO) as House Joint Resolution 56 on May 21, 2003. (Article V of the Constitution of the United States of America requires 2/3 of "both Houses" —the House of Representatives and the Senate— to vote to hold a "convention" to amend the constitution. The "convention" consists of putting the question to the legislatures of the States. Three-quarters of the States must ratify to amend.)
It has gained additional attention since February 6, 2004, when the highest court in Massachussets held that State's constitution prohibits discrimination on the basis of sexual orientation and the legislature must confer all the benefits of marital status upon otherwise qualified homosexuals.
To evaluate the claims for and against this proposed change to the federal Constitution, it is useful to recall how that Constitution works without the amendment.
In theory, one of the advantages of a "federal" system of government is that the semi-autonomous subdivisions ("States" in the United States of America) can each act as a sort of laboratory for each other. New legislative schemes can be tried out in, say, Vermont or Hawaii or California, without changing the law in other places.
A recent example of such a "laboratory experiment" was the de-regulation of electric utilities in California. At the time many other states, including mine, were also considering de-regulation. After providers demonstrated that they could manipulate the system at will to produce rolling blackouts and price gouging, nobody wants to de-regulate the same way California did. Having California as the example of what to avoid is a big improvement over blaming the problem on an abstraction ("de-regulation") or a political party or politician.
There are, of course, countervailing legal structures built into the Constitution. The Founders may have been wrong about slavery but they implemented "checks and balances" quite well. There are many checks on variety of State laws, including all of Congress' powers to enact uniform national laws, which prevail over any contrary state laws under the Supremacy Clause. See U.S. Const., Art. VII, ¶ 2.
More subtle, and more relevant to the debate about a national marriage policy, is something
called the Full Faith and Credit Clause. Article IV, Section 1 of the Constitution provides:
Full Faith and Credit shall be given in each State to the public Acts, Records, and judicial Proceedings of every other State. And the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof.
As applied to marriage, this means that States have to acknowledge and enforce marriages which are lawful in other States. New Mexico, for example, is a community property state with laws inherited from the Spanish civil law system, not the English common law. In this tradition, a "marriage" by cohabitation, also known as a "common law" marriage, is not recognized. New Mexico residents must get a license and have a ceremony performed by a person legally qualifed to "solemnize" a marriage, in order to be considered lawfully married. Under the Full Faith and Credit Clause, however, New Mexico must recognize as valid any "common law" marriage which would be valid in another state. In Texas, for example, cohabitation for a certain period of time can create a lawful marriage, if the couple otherwise indicate an intent to be married, or as we lawyers say, "hold themselves out as man and wife".
Proponents of restricting "marriage" to heterosexuals have already used Congress' power to quarantine experiments with same-sex marriage, by enacting the so-called "Defense of Marriage Act", codified at 28 U.S.C. §1738C.
No State, territory, or possession of the United States, or Indian tribe, shall be required to give effect to any public act, record, or judicial proceeding of any other State, territory, possession, or tribe respecting a relationship between persons of the same sex that is treated as a marriage under the laws of such other State, territory, possession, or tribe, or a right or claim arising from such relationship.
(There is another part of the Defense of Marriage Act which, like the proposed constitutional amendment, restricts the term "marriage" to "a legal union between one man and one woman as husband and wife". 1 U.S.C. §7. Unlike the proposed amendment, however, this definition only applies to federal laws, leaving States free to experiment.)
The Defense of Marriage Act seems to violate the Full Faith and Credit Clause, until you note that Congress may determine the "effect" of one States' acts and proceedings on another. On the other hand, the Defense of Marriage Act expressly discriminates in favor of heterosexuals and against "a relationship between persons of the same sex", which may be unconstitutional if the Supreme Court decides to extend the due process principles of Lawrence v. Texas beyond private sexual conduct to marriage laws. The proposed amendment to the Constitution attempts to insulate legalized discrimination against homosexuals from these potential legal attacks.
The Defense of Marriage Act doesn't usurp entirely a State legislature's prerogative to recognize same-sex marriages, it just prevents the spread of the horrid contagion to other states. The new proposed Federal Marriage Amendment, however, purports to prevent any state from recognizing same-sex marriages. Aside from being poorly written, the amendment has little chance of passage. It is not addressed to a current problem but rather anticipates one: that the Defense of Marriage Act will be declared unconstitutional. I do not believe that this will happen.
I doubt Lawrence v. Texas extends to marriage laws. The government can argue that it has a legitimate interest in regulating marriage. Asking to be left alone in private is one thing, asking to be recognized and approved by the State as a couple is quite another. Unlike private sexual practices, which are not a legitimate concern of the state, marriage is a public institution which is interwoven into the very structure of society. Thus, even if you agree with its policy objectives, those objectives are already served by a federal statute and there is no need for a constitutional amendment. Worse, the proposed amendment is an attempt to set national social policy by referendum, and beyond the reach of the usual, deliberative political process. The last such experiment was Prohibition, and it did not fare well.