Details of gay marriage debate in Pa.

THE LAW: Pennsylvania's 1996 "Defense of Marriage" law defines marriage as being between a man and a woman. It is silent on the matter of civil unions.

THE LEGISLATION: The bill passed by the state Senate on Wednesday would amend the Pennsylvania Constitution to define marriage as between one man and one woman. A bill passed by the state House carries the same definition, but also is geared to outlaw civil unions between gays by banning "a legal union identical or substantially equivalent to that of marriage for unmarried individuals."

CONSERVATIVES: They want a constitutional ban on gay marriages and civil unions between gays to guarantee that no state judge is able to allow either by acting on a legal challenge to state law.

LIBERALS: They say a constitutional amendment is not needed to counter a hypothetical challenge to the state's Defense of Marriage law. They also say civil unions have nothing to do with marriage, and a ban could take away rights from unmarried people who live together, gay or straight.

THE PROCESS: Amending the Pennsylvania Constitution requires the approval by the House and Senate in two successive two-year sessions of the General Assembly and then the approval of voters in a statewide referendum. The earliest a proposed amendment can be placed on the statewide ballot is 2007.