The U.S. Supreme Court just told Arkansas it has to allow both same-sex parents to appear their children's birth certificates.

The plaintiffs in Pavan v. Nathaniel Smith were two sets of married lesbian couples who all conceived using anonymous sperm donors. When the children were born, though, Alabama refused to list both parents on the birth certificates, even though they routinely do so for straight couples that conceive using donor sperm.

The couples sued, but the Arkansas Supreme Court ruled in the state's favor. On Monday, the Supreme Court said reversed the lower court's decision on the grounds that it undermined the 2015 marriage equality decision.

"As we explained [in Obergefell v. Hodges], a State may not 'exclude same-sex couples from civil marriage on the same terms and conditions as opposite-sex couples.'" the decision read. "Indeed, in listing those terms and conditions—the 'rights, benefits, and responsibilities' to which same-sex couples, no less than opposite-sex couples, must have access—we expressly identified 'birth and death certificates.' That was no accident..."

Conservative justices Neil Gorsuch, Clarence Thomas, and Samuel Alito dissented, insisting that "rational reasons exist for a biology-based birth registration regime."

Douglas Hallward-Driemeier, who represented the couples, told the Washington Blade that the ruling “strengthens the rule of law."

"Marriage equality is the law of the land, and this decision sends a clear message that states must follow the law and treat all married couples equally,” he added

Despite Obergefell, same-sex couples continue to face discrimination when it comes to creating families: Since the beginning of 2017, Alabama, South Dakota, and Texas have all passed laws allowing adoption agencies to turn away LGBT couples on religious grounds.