The temporary restraining order issued Monday by U.S. District Magistrate Judge Tim Black allows the male partner of a terminally ill man to be listed as his spouse on a death certificate, The Cincinnati Enquirer reported.
In granting the order sought by James Obergefell and John Arthur, Black said it applied only to the two men.
Obergefell and Arthur have been together for 20 years and were married July 11 in Maryland, which recognizes same-sex marriages.
Arthur has ALS and has "days maybe weeks" to live, Obergefell testified in a hearing Monday.
Bridget Coontz, who represented the governor and attorney, told Black the case was more about gay rights and less about death certificates.
Black accepted the argument by Al Gerhardstein, the men's attorney, that Ohio should recognize same-sex marriages from other states because it recognizes opposite-sex marriages from other states that are not legal in Ohio, such as teenagers who marry before the state's legal age of consent.
Gerhardstein said he believed the decision would "open the door to create a large number of same-sex couples married in other states" who would force the issue to a vote or to be changed by lawmakers.