Same-sex couples and gay rights activists nationwide are celebrating after major victories today in Vermont and last week in Iowa, two states that are paving the way in allowing gay couples to marry.

Lawmakers in Vermont overrode a veto of a marriage-equality bill by Republican Gov. Jim Douglas today. And on April 3, Iowa’s Supreme Court unanimously found unconstitutional a state law limiting marriage to a man and a woman. The ruling was based on equal-protection language in Iowa’s Constitution.

“We have a constitutional duty to ensure equal protection of the law,” the Iowa Supreme Court said. “If gay and lesbian people must submit to different treatment without exceedingly persuasive justification, they are deprived from the benefits of the principle of equal protection upon which the rule of law is founded.”

In Vermont, following the governor’s veto, the House of Representatives passed the same-sex marriage bill by a 100-49 vote after it cleared the state Senate 23-5. In Vermont, a bill needs two-thirds support in each chamber to override a veto.

Vermont became the first state in the country to allow full civil unions for same-sex couples in 2000.

The Iowa Supreme Court ruling came in the case of Varnum v. Brien, which involves six same-sex couples who were initially denied marriage licenses by the Polk County recorder in 2005.

Two years later, a local judge, Robert Hanson, ruled that a 1998 state law defining marriage as only between a man and a woman was unconstitutional. The 2007 ruling led scores of same-sex couples from all over Iowa to rush to the Polk County courthouse to be granted marriage licenses.

But that victory lasted less than a day. Judge Hanson quickly decided to delay additional granting of licenses, saying that the Iowa Supreme Court should weigh in on the matter first.

Same-sex marriages could take effect in the next several weeks in Iowa when the new ruling becomes final. People seeking marriage licenses do not have to prove they live in Iowa counties. Thus same-sex couples from other states will be able to marry there.

Iowa and Vermont will join Connecticut and Massachusetts as the only U.S. states to allow same-sex couples to marry. California permitted same-sex marriages for about six months, until a massive campaign by anti-gay groups led voters to approve a ban through a state referendum, Proposition 8, last November. Prop. 8 is now being challenged in the courts.

Unlike California and other states that have barred same-sex marriages with ballot measures, in Iowa ballot referenda cannot be used to initiate constitutional amendments.

Rather, an amendment would require approval by state lawmakers during two legislative sessions, and then approval by voters at the ballot box. That would mean the earliest a prospective ban could take effect would be in 2012. But the idea seems to have little backing among Iowa lawmakers, and Democrats lead both chambers.

Iowa state Senate Majority Leader Michael Gronstal told The New York Times such an amendment failed in the past and would most likely fail again. “We’re just going to say no to amending our Constitution and putting discrimination into our Constitution,” he said.

Gay rights activists in Iowa point out that the state has a long progressive history and has been a trendsetter in the struggle for civil rights. In a recent statement, Gronstal and Iowa House Speaker Pat Murphy noted that an 1868 Iowa Supreme Court ruling outlawed “separate but equal” schools 85 years before the U.S. Supreme Court did.

Same-sex couples and gay rights and marriage equality activists are cautiously optimistic that momentum from Iowa, and now Vermont, will carry over to other states and, eventually to the federal level. Many see the recent decisions as reflecting a growing movement for change and civil rights.

Illinois State Rep. Greg Harris told The Associated Press last week he believes the Iowa ruling demonstrates the values of basic fairness are spreading across the country. Harris. a Chicago Democrat who is openly gay, has sponsored a bill that would legalize civil unions in Illinois, giving gay couples many of the legal benefits of marriage. The bill passed out of committee in March and now faces a vote on the state House floor. Illinois is one of 14 states restricting marriage to a man and a woman.

Lawmakers in New Hampshire and Maine are also considering bills to allow same-sex marriage. Gay & Lesbian Advocates & Defenders, which helped to legalize gay marriage in Massachusetts and Connecticut, has set a goal of expanding marriage equality to all New England states by 2012. Both Maine and New Hampshire already offer same-sex couples some form of legal protections.

Forty-three U.S. states have laws explicitly prohibiting such marriages, including 29 with constitutional amendments restricting marriages to one man and one woman.

Jon Davidson, legal director for Lambda Legal, a New York based gay rights organization, sees support for allowing same-sex couples to marry moving in the right direction, despite those who oppose it.

“There is certainly strong opposition, with 29 states amending their constitution,” he told The Associated Press after the Iowa ruling. “But this case will provide additional momentum and we can see the day where same-sex marriage is allowed throughout the United States. People are coming to understand that this is inevitable.”

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