Fargo, N.D. (AP) A federal judge is set to decide the future of a lawsuit filed by seven couples challenging the constitutional prohibition on same-sex marriage in North Dakota. The suit opposes both North Dakota's ban on gay marriage and its refusal to recognize marriages of same-sex couples who legally wed in other states. The couples have asked U.S. District Judge Ralph Erickson to rule in their favor without oral arguments. The state has filed a separate motion asking Erickson to throw out the suit. Minneapolis Attorney Josh Newville, who on Monday filed the final brief regarding the two motions, says he's optimistic the court will "declare marriage equality to be the law of the land.'' North Dakota Attorney General Wayne Stenehjem says his office has a duty to defend the ban.