Where do people who believe the Constitution protects gay marriage find this protection? Is it part of privacy protection or something else?
That which is not prohibited is allowed.
The question should not be where the constitution protects “gay marraige,” but where the constitution limits marraige to only a man and a woman…and it doesn’t.
The argument is usually that it violates equal protection.
I refer you to this nice summary of the equal protection clause
There are a number of places proponents of SSM point to. The First Amendment, the Due Process clauses of the Fifth and Fourteenth Amendments, the Fourteenth Amendment’s Equal Protection clause. Since SSM is legal in one state and in a few other countries, proponents also point to the Full Faith and Credit clause, claiming that it requires each state to recognize marriages performed in other states.
None of this has been ruled upon recently by a federal court, although there are a few old cases from 20 or more years ago which rejected the Constitutional claims out of hand. There are currently cases wending their way through the courts in several states (including New Jersey, California, New York, Conneticut, Washington, Oregon and New Mexico) challenging state bans on SSM and at least one federal case filed in Florida challenging the grossly-misnamed “Defense of Marriage Act.”
There have been hundreds of threads on SSM in the last few years. Search.
The constitutional protection for it is claimed to be found in Amendment XIV, Section 1. What extends this to marriage is the ruling that marriage is a “fundamental right” that was made part of constitutional law back in Loving v. Virginia. Coupled with this is the right to autonomy in personal relationships defined in Lawrence v. Texas, though that decision specifically avoided defining whether that right extended to legal recognition of marriage.
However, the Supreme Court has declined, up to this point, to rule on the above claim – either way. AFAIK, the sole instance in which the Supreme Court has considered such a case is in denying cert. to Singer v. Hara, out of the State of Washington, back in 1974.
This is probably more of a great debate, but those people who find a Constitutional right to gay marriage generally find it in one of two places. The first draws itself from the idea, derived from common law, implied in the bill of rights and 14th amendment, and set out in various supreme court decisions (Griswold v. Connecticut, Roe v. Wade, etc) that people have a basic right to privacy, which extends to their relationships with each other, and that people have a right to (among other things)make whatever kind of family they want. So, if a gay couple want to marry, it’s not the proper role of the government to say they can’t.
The second argument made is one of equal protection. There’s a principle in the law, and stated in the 14th amendment, that everyone enjoys the “equal protection of the law”. The government can’t favor one group or class of people over another, unless it has a good reason to do so. Usually, the idea of “a good reason” is interpreted really loosely. This is called a “rational basis” test. So, the government can pass a law saying that you have to be at least 16 in order to drive, for example. That law does treat people differently, but the law has a “rational basis”. y. However, there are some categories where equal protection is treated more strictly…this is called “strict scrutiny”. Categories like race fall under the strict scrutiny rule. If sexual orientation is considered a category where “strict scrutiny” is applied (It’s not generally considered to be now, but some people think it should), then a law that lets straight people get married but not gay people probably wouldn’t pass the “strict scrutiny” test.