This article is from the archive of our partner National Journal

What the Supreme Court thinks about same-sex marriage is really a question of what Justice Anthony Kennedy thinks about same-sex marriage. And on Tuesday, we will get to see how far Kennedy—and the Court—is willing to go in recognizing a constitutional right for all couples to marry.

The Court is scheduled to hear oral arguments Tuesday morning in a set of cases that could legalize same-sex marriage in every state as soon as this summer. And over the two and a half hours of arguments—more than twice the time most cases receive — all eyes will be on Kennedy.

Couples from four states—Kentucky, Michigan, Ohio, and Tennessee—are challenging state laws that either ban same-sex marriage or refuse to recognize same-sex marriages from other states. The question before the Court appears simple: Do those laws violate the 14th Amendment to the Constitution?

(RELATED: Can Same-Sex Marriage Lose?)

Here's what to watch for on Tuesday:

Kennedy on Kennedy

The same-sex couples challenging gay-marriage bans say Kennedy has already laid the foundation for a ruling in their favor. No, he hasn't, the states argue. His fellow justices aren't sure. So, what does he think?

Written briefs in Tuesday's cases spend a lot of time discussing U.S. v. Windsor, the 2013 ruling written by Kennedy that struck down a key part of the federal Defense of Marriage Act. While Kennedy said DOMA was unconstitutional, his reasoning was unclear. (Justice Antonin Scalia called Kennedy's opinion "legalistic argle-bargle.") And that has opened up a debate over whether the principles in Windsor apply now.

"The Windsor opinion itself created as many questions as it answered," Stanford University law professor Jane Schacter said.

(RELATED: 36 States and Counting: Mapping the Legalization of Gay Marriage)

Attorneys defending state bans on same-sex marriage describe Windsor as a decision about the balance of state and federal power. Kennedy called the law a "federal intrusion on state power" and said DOMA was unconstitutional because it denied marriage benefits even to people in states that had legalized same-sex marriage.

Opponents of same-sex marriage therefore read Windsor as a ruling that elevated states' right to make their own decisions about marriage—including the decision not to recognize same-sex unions.

But Kennedy's decision in Windsor also said that DOMA forced same-sex couples into "second-tier marriage," which "demeans the couple, whose moral and sexual choices the Constitution protects" and "humiliates tens of thousands of children now being raised by same-sex couples."

State laws restricting same-sex marriage do all the same things, supporters of marriage equality argue, and therefore are also unconstitutional.

(RELATED: The Legal Argument Gay Republicans Are Making In Favor of Same-Sex Marriage)

"Whether recognition is denied by state or federal government, the impingement on equal dignity for individuals is every bit as severe," the couples challenging Kentucky's marriage laws said in a brief to the Court.

What's the legal standard?

The couples challenging bans on same-sex marriage are hoping for a sweeping ruling from the Court—one that would declare a fundamental right to marry and would set a heightened legal standard for evaluating other laws that appear to discriminate against gay people.

Whether the ruling ultimately goes that far will depend in part on how the justices—again, mainly Kennedy—tackle the legalistic details of the case.

In most cases, when a law treats two groups of people differently, government has to prove only that it has a "rational basis" for doing so. But when laws appear to discriminate against people on the basis of factors like race and sex, the courts apply a higher standard, making those laws harder to defend.

(RELATED: The One Election Where Gay Marriage Is Still a Political Liability for Democrats)

Kennedy has consistently pushed the Court toward embracing gay rights, but he hasn't always spelled out the standards he has used. The couples in Tuesday's cases say the Court should clearly embrace a heightened degree of legal scrutiny, as a safeguard against discrimination.

"Making explicit that laws discriminating on the basis of sexual orientation are not presumptively constitutional is necessary to affirm the equal dignity of gay people," wrote the challengers to Ohio's ban on recognizing same-sex marriages from other states.

Is there a middle ground?

The court had a chance in 2013 to go all-in on marriage equality in the states. It punted, falling back on procedural issues to avoid a ruling on the constitutionality of state laws that restrict same-sex marriage. The big question Tuesday will be whether Kennedy is ready to go all the way this time.

If he's not, it will be harder to find a way out, legal experts say. There's one obvious option. The Court is hearing arguments on two separate questions: whether the Constitution requires states to certify same-sex marriages, and whether it requires them to recognize same-sex marriages from other states. At least theoretically, it is possible the Court could say that states don't have to let their residents get married, but that they must recognize same-sex marriages performed in states that allow it. Practically, that would expand same-sex couples' legal rights in every state, but it would also create a patchwork that advocates still see as fundamentally unequal.

"When two people join their lives together through marriage, they vow mutual support and care without reference to state lines," the Kentucky couples' brief says.

Kennedy on Kennedy

The same-sex couples challenging gay-marriage bans say Kennedy has already laid the foundation for a ruling in their favor. No, he hasn't, the states argue. His fellow justices aren't sure. So, what does he think?

Written briefs in Tuesday's cases spend a lot of time discussing U.S. v. Windsor, the 2013 ruling written by Kennedy that struck down a key part of the federal Defense of Marriage Act. While Kennedy said DOMA was unconstitutional, his reasoning was unclear. (Justice Antonin Scalia called Kennedy's opinion "legalistic argle-bargle.") And that has opened up a debate over whether the principles in Windsor apply now.

"The Windsor opinion itself created as many questions as it answered," Stanford University law professor Jane Schacter said.

(RELATED: 36 States and Counting: Mapping the Legalization of Gay Marriage)

Attorneys defending state bans on same-sex marriage describe Windsor as a decision about the balance of state and federal power. Kennedy called the law a "federal intrusion on state power" and said DOMA was unconstitutional because it denied marriage benefits even to people in states that had legalized same-sex marriage.

Opponents of same-sex marriage therefore read Windsor as a ruling that elevated states' right to make their own decisions about marriage—including the decision not to recognize same-sex unions.

But Kennedy's decision in Windsor also said that DOMA forced same-sex couples into "second-tier marriage," which "demeans the couple, whose moral and sexual choices the Constitution protects" and "humiliates tens of thousands of children now being raised by same-sex couples."

State laws restricting same-sex marriage do all the same things, supporters of marriage equality argue, and therefore are also unconstitutional.

(RELATED: The Legal Argument Gay Republicans Are Making In Favor of Same-Sex Marriage)

"Whether recognition is denied by state or federal government, the impingement on equal dignity for individuals is every bit as severe," the couples challenging Kentucky's marriage laws said in a brief to the Court.

What's the legal standard?

The couples challenging bans on same-sex marriage are hoping for a sweeping ruling from the Court—one that would declare a fundamental right to marry and would set a heightened legal standard for evaluating other laws that appear to discriminate against gay people.

Whether the ruling ultimately goes that far will depend in part on how the justices—again, mainly Kennedy—tackle the legalistic details of the case.

In most cases, when a law treats two groups of people differently, government has to prove only that it has a "rational basis" for doing so. But when laws appear to discriminate against people on the basis of factors like race and sex, the courts apply a higher standard, making those laws harder to defend.

(RELATED: The One Election Where Gay Marriage Is Still a Political Liability for Democrats)

Kennedy has consistently pushed the Court toward embracing gay rights, but he hasn't always spelled out the standards he has used. The couples in Tuesday's cases say the Court should clearly embrace a heightened degree of legal scrutiny, as a safeguard against discrimination.

"Making explicit that laws discriminating on the basis of sexual orientation are not presumptively constitutional is necessary to affirm the equal dignity of gay people," wrote the challengers to Ohio's ban on recognizing same-sex marriages from other states.

Is there a middle ground?

The court had a chance in 2013 to go all-in on marriage equality in the states. It punted, falling back on procedural issues to avoid a ruling on the constitutionality of state laws that restrict same-sex marriage. The big question Tuesday will be whether Kennedy is ready to go all the way this time.

If he's not, it will be harder to find a way out, legal experts say. There's one obvious option. The Court is hearing arguments on two separate questions: whether the Constitution requires states to certify same-sex marriages, and whether it requires them to recognize same-sex marriages from other states. At least theoretically, it is possible the Court could say that states don't have to let their residents get married, but that they must recognize same-sex marriages performed in states that allow it. Practically, that would expand same-sex couples' legal rights in every state, but it would also create a patchwork that advocates still see as fundamentally unequal.

"When two people join their lives together through marriage, they vow mutual support and care without reference to state lines," the Kentucky couples' brief says.

This article is from the archive of our partner National Journal.

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