Same-Sex Marriage Cases Hinge on Big Legal Issues

Such as, whether gays and lesbians are a "vulnerable group" covered by civil rights laws

As the U.S. Supreme Court prepares to take up same-sex marriage next month, laws barring recognition of such unions are not the only issue hanging in the balance. The very question of whether gay people constitute a vulnerable group that needs the court's help in asserting equal rights is also at stake.

Ahead of two high-profile oral arguments in March, backers of gay rights and defenders of more traditional marriage are zeroing in on whether courts should be wary of any laws that target gay people.

The underlying question is whether bans on gay marriage violate the U.S. Constitution's guarantee of equal protection under the law.