In anticipation of a Washington State Supreme Court ruling favoring same-sex marriage, a gay-rights organization is preparing now to help gay and lesbian couples with plans for immediate weddings.

The high court's decision could come this fall in a lawsuit by 19 gay and lesbian couples across the state who are seeking the right to marry here, or to have their marriages from elsewhere recognized in this state.

Equal Rights Washington believes that if the ruling allows gays to marry, couples may be able to apply for marriage licenses on the day the ruling is issued — typically that would happen on a Thursday — and that weddings then could take place following a three-day waiting period.

"We are talking about the best case scenario — and saying, 'Let's have a wedding on Sunday,' " said Fran Dunaway, executive director of Equal Rights Washington.

Dunaway said while there's no way to know how or when the court will rule, the group wants to be prepared to answer questions couples might have about the ramification of the ruling. Equal Rights would prepare a sort of check-list for couples who are prepared to wed in three days.

"Anything that can be taken care of ahead of time, so it's not just a scramble, we want to offer to couples who might be interested," Dunaway said. "There'll be dresses to buy; suits to iron, flowers to be picked up. It would be a powerful experience for a lot of people."

Gay and lesbian couples are challenging the constitutionality of the state's Defense of Marriage Act, or DOMA, which was passed by the Legislature in 1998 and defines marriage as a union between one man and one woman.

The nine justices of the Supreme Court heard oral arguments in the case March 8. Attorneys in the case have said a ruling is likely this fall.

They see three possible outcomes:

• The court could upholding DOMA, meaning gays and lesbians would not be allowed to marry.

• The court could ask the Legislature to resolve the issue.

Activists on both sides are preparing for each possible outcome.

Joseph Fuiten, pastor of the Cedar Park Assembly of God church in Bothell, said, "Our celebration will be that they won't get married. It will be a blank picture."

Fuiten, who also heads a statewide evangelical lobby group, added, "For them it's personal. For us it's about policy. We're gearing up, and will respond on the day of."

Also on that day, Don't Amend Washington, another gay-rights activist organization, plans a rally in Seattle's Volunteer Park — regardless of the outcome.

Lornet Turnbull: 206-464-2420