OKLAHOMA CITY (AP) — The Cherokee Nation’s attorney general legalized gay marriage for the country’s second-largest Native American tribe, saying its same-sex marriage ban violates a tribal requirement for all of its citizens to be treated equally.

Attorney General Todd Hembree’s opinion, which was issued Friday, says parts of a 2004 tribal law that defined marriage as “a civil contract between one man and one woman” and prohibited marriage between two persons of the same sex violate the Cherokee Constitution, which requires the equal treatment of tribal citizens.

“The right to marry without the freedom to marry the person of one’s choice is no right at all,” Hembree wrote in his opinion.

Tribal Assistant Attorney General Chrissi Nimmo said Monday that the opinion carries the force of law and legalizes same-sex marriage and adoption by same-sex couples who are members of the Oklahoma-based tribe, which has about 300,000 members.

The Cherokee Nation was among 11 of the nation’s 567 federally recognized tribes that had explicit bans on gay marriage.

Nimmo said the sovereign laws of the Cherokee Nation and other tribes were not directly affected by last year’s U.S. Supreme Court decision legalizing same-sex marriage and that Indian tribes are the only remaining governments in the U.S. that can prohibit or legalize same-sex marriage. But the Cherokee Nation Constitution contains similar due process and equal protection guarantees as the U.S. Constitution, rights that are reflected in the tribal opinion, she said.

“It’s a very similar decision to that of the United States Supreme Court,” she said.

The tribe’s same-sex marriage ban was part of the Cherokee Nation Marriage and Family Act that was approved unanimously by the tribal council. Cherokee Nation Principal Chief Bill John Baker, who was a member of the tribal council at the time and voted for the measure, did not immediately respond to a phone message Monday seeking comment.

Hembree’s opinion was requested by the director of the tribe’s tax commission, who had asked whether the tribe could issue a vehicle tag to a same-sex couple married outside the tribe’s jurisdiction. The couple is not identified in the opinion.

The matter arose when a person who was recently married outside the tribe’s jurisdiction offered a marriage certificate issued to her and another woman as proof of her identity, according to the ruling. The commission was unsure whether it could accept the same-sex marriage certificate in light of the tribe’s prohibition of same-sex marriage.

“We were having to deal with this kind of thing on a daily basis,” Nimmo said. “Administratively and practically, it makes things easier.”