A ruling by the U.S. Supreme Court is expected in the spring of 2016 on a case stemming from the Mississippi Band of Choctaw Indians which challenges whether non-Indians can be sued in American Indian courts.

The Supreme Court heard arguments in the case on Monday.

The case, brought by the Dollar General Corp. against the Tribe, stems from a civil lawsuit brought against Dollar General in Choctaw courts.

The Tennessee-based company was sued in 2005 over allegations that a store manager made sexual advances toward a 13-year-old boy placed in his store by a tribal youth employment program. Federal authorities control criminal prosecutions on reservations and did not bring charges in the case.

Tribal Chief Phyliss J. Anderson, several members of the Choctaw Tribal Council and other Tribal officials were in attendance at Monday's hearing in Washington, D.C.

"Today is a significant day for our Tribe and for all tribes across the country," Anderson said. "This morning I was proud to be at the argument before the nation's highest court addressing a critical element of tribal sovereignty involving tribal courts and jurisdiction over tribal territory."

"If tribal sovereignty means anything, it must include the ability for tribal courts to hear and decide cases arising from activity and conduct on our tribal lands. Businesses like Dollar General that choose to conduct their business on tribal lands should not seek to avoid legal responsibility in a tribal forum when actions of their employees result in harm to tribal citizens.

"I want to thank the United States and, in particular, the State of Mississippi as well as the other states which joined with our Tribe and other tribal organizations for their support of tribal sovereignty in this case."

A previous Supreme Court decision found that nonmembers can't be sued in tribal court, except when they've consented to dealings with the tribe, for example through a contract, lease or other business arrangement. However, tribal and lower federal courts have ruled that the boy's parents can pursue the civil suit, seeking $2.5 million, in tribal court.

They note that Dollar General signed a lease in the tribe's on-reservation shopping center stating that disputes would be taken to Choctaw court and governed by tribal law. They also note the store further entangled itself with the tribe when it voluntarily agreed to participate in the employment program, in which the tribe paid wages, not the store.

Dollar General, though, claims that because Congress hasn't specifically allowed such lawsuits, the Supreme Court should ban them. They say that the Choctaws are trying to overextend their courts' limited authority.

The case is being closely watched by other Indian tribes nationwide, who warn that Dollar General could gut the authority of tribal courts and infringe on tribal sovereignty. The federal government has weighed in on behalf of the 10,000-member Choctaw band, as has Mississippi Attorney General Jim Hood, who wrote that granting Dollar General's appeal would be an "unwarranted assault" on the Choctaw courts. Colorado, New Mexico, North Dakota, Oregon and Washington also sided with the tribe.

Taking Dollar General's side are attorneys general from Oklahoma, Wyoming, Utah, Michigan, Arizona, and Alabama. The retailer and its supporters warn that a victory for the Mississippi Choctaws could create a rush of lawsuits in tribal courts. They raise concerns that some tribal courts rely on unwritten law, and that tribal courts could be biased.

In a legal brief, Dollar General argued that "outsiders" could be treated unfairly in tribal courts due to "the lack of judicial training and independence" of those courts. It said this gives "rise to the risk that the law a business reasonably expected to govern its conduct will not be the law applied to it."

The Choctaws deny such concerns. The tribe says that almost 5,000 cases have been heard since 2013 involving parties who aren't members of the tribe, and that more than 85 percent of those cases have resulted in victories or settlement for the non-Indian party. The Choctaws say Dollar General had fair notice of tribal jurisdiction.

"What businesses may not do is enter tribal land, engage in extensive interactions with the tribe and its members, and then seek to avoid repercussions for the harm inflicted on one of the tribe's members based on spurious legal arguments and unfounded attacks on tribal justice," the tribe wrote in a legal brief.

- The Associated Press contributed to this story.