The US Supreme Court has ruled nearly half of Oklahoma belongs to Native Americans in a landmark case that quashed a child rape conviction.

The court decided 5-4 that the eastern part of the state, including its second-largest city, Tulsa, should be recognized as part of the reservation.

The case was brought by Jimcy McGirt, who was convicted in 1997 of raping a girl. He cited the historical claim of the Muscogee (Creek) Nation to the land where the assault occurred.

Thursday's ruling in McGirt v. Oklahoma is seen as one of the most far-reaching cases for Native Americans before the highest of the United States courts in decades.

In particular, the decision casts doubt on hundreds of convictions obtained by local authorities, as it means that certain members of the tribe found guilty in state courts for crimes committed on the property will now appeal their convictions.

The decision, written by Justice Neil Gorusch, takes away the power of Oklahoma prosecutors to bring criminal charges against Native American suspects in large areas of Oklahoma.

Only federal prosecutors will have the ability to criminally prosecute Native Americans accused of crimes in the land.

However, Chief Justice John G. Roberts Jr. warned the court's decision would wreak havoc on Oklahoma's criminal justice system, saying that the state's ability to prosecute serious crimes "will be hobbled and decades of past convictions could well be thrown out."

"The court has profoundly destabilized the governance of eastern Oklahoma," he added.

His comments came after the Department of Justice raised questions about how federal prosecutors would deal with new investigations that they would suddenly be responsible for investigating.

Justice Neil Gorsuch was more pessimistic, though, telling The Guardian "It is unclear why pessimism should rule the day. Over time, Oklahoma and its Tribes have proven they can work successfully together as partners."

"This is a historic day," Principal Chief David Hill said to The New York Times. "This is amazing. It's never too late to make things right."

Many on social media, who celebrated the decision with the statement "Native Lives Matter" echoed his thoughts.

According to the Reuters News Agency, members of the tribe who live within the boundaries may also be excluded from state taxes.

About 1.8 million residents, 15% of whom are native Americans, live on land covering three million acres.

Justice Neil Gorsuch, a conservative appointed by President Donald Trump, sided with the court's four liberals and wrote the opinion. He referred to the Trail of Tears, the forced relocation of Native Americans in the 19th Century, including the Creek Nation, to Oklahoma.

At the time, the US government said that the new land will forever belong to the tribes.

"Today we are asked whether the land these treaties promised remains an Indian reservation for purposes of federal criminal law," Justice Gorsuch wrote.

"Because Congress has not said otherwise, we hold the government to its word." She continued.

The decision reversed McGirt's jail term. Nevertheless, he could also be tried in the federal court. McGirt, now 71, was convicted in 1997 of raping a four-year-old child in Wagoner County.

He did not dispute his crime before the Supreme Court but argued that only federal authorities should have been entitled to prosecute him. That's because McGirt is a member of the Seminole Nation.

"The Supreme Court reaffirmed today that when the United States makes promises, the courts will keep those promises." McGirt's lawyer, Ian Heath Gershengorn, said to CNBC.

In a dissenting opinion, Chief Justice John Roberts argued that the ruling would destabilize the courts of the state.

"The State's ability to prosecute serious crimes will be hobbled and decades of past convictions could well be thrown out.

"The decision today creates significant uncertainty for the State's continuing authority over any area that touches Indian affairs, ranging from zoning and taxation to family and environmental law," the Chief Justice wrote.

Research by the Atlantic Magazine of the Oklahoma Department of Corrections found that 1,887 Native Americans were in jail at the end of last year for crimes committed within tribal territories.

But less than one in ten of those cases, according to the research, would qualify for a new federal trial.

Jonodev Chaudhuri, former Chief Justice of the Supreme Court of the Muscogee Nation, dismissed the case of legal chaos.

"All the sky-is-falling narratives were dubious at best," he said to the Tulsa World newspaper. "This would only apply to a small subset of Native Americans committing crimes within the boundaries."

In a joint statement, the Five Tribes of Oklahoma - Cherokee, Chickasaw, Choctaw, and Seminole and Muscogee Nation - welcomed the decision.

They agreed to collaborate with federal and state authorities to decide on mutual authority over the land.

"The Nations and the state are committed to implementing a framework of shared jurisdiction that will preserve sovereign interests and rights to self-government while affirming jurisdictional understandings, procedures, laws and regulations that support public safety, our economy and private property rights," the statement said.

Oklahoma's three U.S. attorneys made a joint statement shortly after the decision, expressing faith that "tribal, state, local and federal law enforcement will work together to continue providing exceptional public safety."

Many People expressed their opinion about what they called 'victory' to the natives…