Two cases will be heard by the Supreme Court this week, starting tomorrow, which will have an impact (even if it is a wash) on same-sex marriage throughout the country.

The first case is a 2008 ballot initiative in California known as Proposition 8, which defines marriage in the state constitution as a legal union of one man and one woman. The second case is a challenge to the 1996 federal Defense of Marriage Act (DOMA), which for purposes of federal benefits also defines marriage as a union of one man and one woman.

Lawyers challenging the measures argue that Prop. 8 and DOMA violate the rights of same-sex couples by treating them like second-class citizens. “With the full authority of the State behind it, Proposition 8 sends a clear and powerful message to gay men and lesbians: You are not good enough to marry. Your loving relationship is not equal to or respected enough to qualify to be called a marriage,” writes Washington lawyer Theodore Olson in his brief seeking to overturn Prop. 8.

On the other side, lawyers counter that it is proponents of same-sex marriage who are seeking to change an institution that has existed throughout history as the symbolic joining of male and female. Preservation of this tradition is not discrimination, they say.

“Providing special recognition to one class of individuals does not demean others who are not similarly situated,” writes Washington lawyer Charles Cooper in his brief urging the court to uphold Prop. 8. “It is simply not stigmatizing for the law to treat different things differently, or to call different things by different names.”

Lurking in the background with both of the cases is a separate issue: “standing”.  “Standing” means whether or not the party in the lawsuit has the right to be there.  DOMA is a federal law, which means that the federal government — the Obama Administration — should be defending its constitutionality.  Prop 8 is a California law, which means that the California government — the Brown administation — shold be defending its constitutionality.

But both Obama administration and the Brown administration (as well as the previous Schwartzenager administration) have concluded that DOMA/Prop 8 are indeed constitutional, and chose not to defend them.  So who is defending DOMA before the Supreme Court?  The Republicans in Congress have hired lawyers to do it.  And who is defending Prop 8?  Special interest lawyers paid by groups like Focus on the Family.

And there rests an issue, in both cases, as to whether the party defending the law has “standing”.

But setting standing aside, the most basic question at the heart of the debate over same-sex marriage is whether the US Constitution protects a fundamental right to marry regardless of sexual orientation.

Gay marriage proponents say it clearly does. Supporters of traditional marriage counter that the Supreme Court has never recognized such a right. They cite a 40-year-old precedent, Baker v. Nelson, that upheld a Minnesota law restricting marriage to one man and one woman.

But that’s not the precise issue before the court. The justices have agreed to examine whether same-sex couples are entitled – under the Constitution’s equal protection provisions – to be treated equally when it comes to marriage and the benefits of marriage.

And even if the court says, yes, same-sex couple should be treated equally, there still remains a question of whether or not that actually means it must be called marriage.

And a question of whether that should apply to ALL the states.

In looking to devine where the court will go, the most considered case is Lawrence v. Texas, decided eight years ago.  That case involved a Texas law which prohibited sodomy, but only homosexual sodomy.   “Swing” justice Kennedy ultimately decided that violeted equal protection and discriminated against homosexuals.  In writing the opinion in Lawrence, Kennedy took great pains to say the case had no bearing on same-sex marriage.  In his dissent, Scalia wrote “don’t believe that”, arguing that once you establish gays as a class to be protected under the law, then same-sex marriage is the next thing to be allowed.

And he may be right.

To prevail at the high court, supporters of California’s Prop. 8 and DOMA must be able to offer a persuasive justification for treating gay and lesbian couples differently from heterosexual couples.

Because of the Lawrence decision, they can’t argue that society views homosexual conduct as immoral. That argument is off the table.

Instead, proponents of the traditional view of marriage argue that the government is entitled to grant preferential treatment to couples of the opposite sex to encourage what it considers the ideal arrangement for raising children: two biological parents in a stable home, providing male and female role models for their own children.

Traditional marriage supporters contend that the institution would be irrevocably eroded to the detriment of biological fathers and mothers – and children – if same-sex marriages are permitted. Such views are influenced by religious beliefs, biblical teachings, and people’s own sense of morality.

Gay marriage proponents counter that same-sex couples are ca-pable of raising well-adjusted children in stable, loving homes just as well as married heterosexual couples. Male-female procreation can’t be a qualification for marriage, they say, because infertile couples and the elderly are allowed to wed with no inquiry into their ability or propensity to make babies.

Lawyers for same-sex couples want Kennedy to take up where he left off in the Lawrence decision and establish heightened civil rights protections for gay and lesbian Americans like those for African-Americans and women.

In contrast, lawyers supporting traditional marriage are seeking to channel that part of Kennedy that found it necessary to write the disclaimer in the Lawrence decision.

One of their strongest arguments is that it is not the right time for the high court to intervene in the same-sex marriage debate. Gays and lesbians are beginning to achieve political success at the state and national level, but the vast majority of states still maintain the traditional definition of marriage. There is no critical mass of states seeking change.

By the time the high court declared bans on interracial marriage unconstitutional in the Loving case in 1967, all but 16 states had already repealed their anti-miscegenation laws. In 1960, all 50 states had anti-sodomy laws. By 2003 when the high court declared such laws invalid in the Lawrence decision, 37 states had already repealed their sodomy laws. Only 13 still had them on the books.

Contrast that with the current landscape for same-sex marriage. Nine states, and the District of Columbia, recognize it – but 41 do not. “I’m unaware of Justice Kennedy ever having voted to strike down the laws of 41 states,” Carpenter says.

Still, with so many variables (including the issue of standing), there are any number of possible outcomes.  Perhaps the court will ultimately let one (or both) cases turn on the standing issue, and not reach the same-sex/equal protection issue at all.  Maybe they strike down Prop 8 in California for reasons limited to that state (gays were given the right to marry before Prop 8 passed), but not let it spread to other states.  Or maybe they will say that ANY state which forbids gays to marry is violating the U.S. Constitution.

Anyway, the circus starts tomorrow, and court-watrcher will be paying close attention to the kinds of questions that are asked, especially by Kennedy and Roberts.