In 19 states and the District of Columbia, gay couples already can wed, with Oregon and Pennsylvania becoming the latest to join the list this week when federal judges struck down their bans and officials decided not to appeal.
South Dakota Attorney General Marty Jackley has said he's obligated by law to defend both the state constitution and state statutes.
He's among the defendants that also include Gov. Dennis Daugaard, Health Secretary Doneen Hollingsworth, Public Safety Secretary Trevor Jones, Pennington County Register of Deeds Donna Mayer and Brown County Register of Deeds Carol Sherman.
Five of the couples already got married in Iowa, Connecticut and Minnesota. The sixth couple was denied a marriage license Thursday, Newville said.
Nancy Rosenbrahn, of Rapid City, married her longtime partner in April in Minneapolis and said it doesn't matter which state is first or last.
"I think what matters is that we're all sending a message to either the Supreme Court or the legislators in Washington, D.C., that this has got to stop," she said Wednesday.
The lawsuit, filed by Minneapolis attorney Josh Newville, claims three violations that are guaranteed in the 14th Amendment to the U.S. Constitution: deprivation of equal protection, due process and right to travel.
"The State will incur little to no burden in allowing same-sex couples to marry and in recognizing the lawful marriages of same-sex couples from other jurisdictions on the same terms as different-sex couples, while the hardship to Plaintiffs of being denied due process, equal protection, and privileges or immunities is severe, subjecting them to an irreparable denial of their constitutional rights," it states.
The complaint seeks a declaration that the statute and constitutional bans are unconstitutional and asks that the defendants be prevented from enforcing the bans and be required to issue marriage licenses to same-sex couples and recognize gay marriages from other states. It also seeks reimbursement for lawyers and other costs.
North Dakota voters in 2004 overwhelmingly passed a constitutional ban on same-sex marriage.
Newville said several couples from North Dakota have contacted him about possibly representing them for a legal challenge in that state, which he's seriously considering.
On Wednesday, Thompson, North Dakota, Mayor Karyn Hippen became the first in the state to join a national coalition of mayors who support same-sex marriage. Although 73 percent of the voters favored the constitutional ban, Hippen said she believes there's support in the state for the issue.
Same-sex marriage advocates in both North Dakota and South Dakota said the fact that sexual orientation and gender identity are not protected classes for matters such as housing and employment has discouraged couples from coming forward.
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