Opponents sought to keep the bill in committee for more hearings, if only to clear up the meaning of the amendment's wording on civil unions and how it could impact the current legal rights of gay and lesbian couples.
One supporter, Sen. John Gordner, R-Columbia, insisted that the wording of the ban on civil unions would not affect current rights, such as a domestic partner's health care coverage or ability to grant power of attorney.
"It does preserve existing legal rights between gay and lesbian couples," Gordner said.
The proposed amendment reads, "No union other than a marriage between one man and one woman shall be valid or recognized as marriage or the functional equivalent of marriage by the Commonwealth."
One opponent of the bill, Sen. Jay Costa, D-Allegheny, questioned whether "functional equivalent" would endanger the health care coverage extended by the city of Pittsburgh to domestic partners of employees.
Sen. Pat Browne, R-Lehigh, who also voted against the measure, said those words leave it unclear exactly which legal rights amount to the equivalent of marriage. It is the Senate's duty to make sure voters understand that before a referendum is held, he said.
"To let people make a determination at the ballot box ... is inappropriate," Browne said.
Pennsylvania's 12-year-old "Defense of Marriage" law defines marriage as being between a man and a woman. However, it is silent on the matter of civil unions, which Gordner said are banned by 19 states.
In 2006, the House approved a ban on civil unions, but the proposal died in the Senate.
Supporters say a constitutional ban on gay marriage and civil unions is necessary to ensure that a judge does not overturn the marriage law.
Opponents of the measure, including advocates for children and victims of domestic violence, have argued that the amendment would prevent same-sex couples and unmarried heterosexual couples from adopting. They also say it would discourage employers from offering domestic-partner benefits.
A constitutional amendment requires approval from both legislative chambers in two consecutive two-year sessions and ultimate approval in a statewide referendum. The earliest that could happen is 2009.
