WASHINGTON - Native Americans have expressed concern about President Donald Trump's pick for Supreme Court justice, Brett Kavanaugh, whose confirmation hearings began this past week in Washington. Many believe that Kavanaugh does not recognize the sovereignty of tribes, which govern themselves as independent nations within the United States.

Tribal nations, through hundreds of treaties with the government, ceded more than half a billion hectares of land in exchange for reservations, services, protections and rights — chief of which was sovereignty, the right to rule themselves and make decisions about how to use their own land.

Their sovereignty, they argue, was recognized by America's founding fathers and is implicit in the wording of the U.S. Constitution, which gives Congress the power "to regulate commerce with foreign nations, and among the several states, and with the Indian tribes."

But the nature of the relationship began to change in the 19th century.

"We went from an era of sovereign-to-sovereign relationships into an era of military conquest by the U.S. of tribes and their territories," said Harvard University international economics professor Joseph P. Kalt, an expert on tribal sovereignty.

During the War of 1812, Native American tribes los During the War of 1812, Native American tribes lost sovereignty of their lands across the "Old Northwest," eventually leading to removals of Indian communities to reservations west of the Mississippi. During the War of 1812, Native American tribes lost sovereignty of their lands across the "Old Northwest," eventually leading to removals of Indian communities to reservations west of the Mississippi.

After the Indian wars ended in the late 1800s, the federal government began inserting itself into tribal affairs through a series of laws aimed at abolishing tribal sovereignty and forcing Indians to assimilate into U.S. society and culture.

But decades later, in the 1970s, Congress passed laws promoting local self-government by tribes. Today, like states, tribes have the right to pass, enforce and interpret their own laws. They have their own police, courts and taxation systems. Additionally, they have the ability to enforce federal laws and determine how tribal land is used.

A law enforcement officer passes a tax protest on A law enforcement officer passes a tax protest on the Tuscarora Indian Nation in New York, Sept. 1, 2010. A federal judge had temporarily blocked New York state's plans to tax cigarette sales by two Native American Nations to non-Native customers; tribes challenged the policy shift as a threat to their sovereignty. A law enforcement officer passes a tax protest on the Tuscarora Indian Nation in New York, Sept. 1, 2010. A federal judge had temporarily blocked New York state's plans to tax cigarette sales by two Native American Nations to non-Native customers; tribes challenged the policy shift as a threat to their sovereignty.

Republican support for tribal self-determination, however, has waned in the last decade or so, Kalt said.

"Tribes depend pretty heavily on lots of federal statutes to create a place for tribes to govern — things like the Indian Child Welfare Act, the authority of the Interior Department to acquire land in trust for tribes so that they can expand their land bases," said Matthew L. M. Fletcher, a member of the Grand Traverse Band of Ottawa and Chippewa Indians in Michigan and a law professor at Michigan State University's College of Law. "But when lower court cases get to the Supreme Court, in some cases, a 200-year precedent doesn't seem to matter."

He said many tribes worry that if a conservative Republican like Kavanaugh is confirmed, the Supreme Court could reverse some of the gains they've made over the last 40 years, particularly with regard to the environment.

"There is no way that a judge like Kavanaugh would have been nominated to the Supreme Court unless he were willing to restrict federal environmental regulations," said Fletcher, pointing to Kavanaugh's record on the District of Columbia Court circuit, in which he consistently argued against measures to protect clean air and water.

America Indians and their supporters protest outsi America Indians and their supporters protest outside of the White House, March 10, 2017, in Washington, to rally against the construction of the disputed Dakota Access oil pipeline. America Indians and their supporters protest outside of the White House, March 10, 2017, in Washington, to rally against the construction of the disputed Dakota Access oil pipeline.

Indian reservations today sit on enormous reserves of coal, oil, gas and uranium. While some tribes, dubbed "energy tribes," depend on energy extraction and support Trump's energy policies, most tribes either lack resources or choose not to explore them.

"The Trump administration is absolutely driven to support fossil fuel and mineral extraction, and there is no way that a judge like Kavanaugh would have been nominated unless he was very favorable toward natural resource extraction," said Fletcher, outlining a scenario by which tribes could lose their land bases altogether.

"Let's say one of those energy tribes is approached by members of Congress or the Interior Department with a proposal promising economic benefits to tribes if they will disestablish their reservation, turn it into private land and proceed with energy extraction," he said.

With such an agreement, the federal government would drop out of the trust relationship with that tribe.

"And I can see tribes agreeing to go along with that — tribes in Alaska or Oklahoma, tribes with natural resources that complain about the federal government putting up too many restrictions on their ability to exploit their economic interests," he said.

And if just one tribe were to accept such a deal, he added, every tribe would find itself pressured to follow suit.

The National Congress of American Indians (NCAI) has urged tribal leaders to watch the confirmation hearings carefully, noting that Justice Anthony Kennedy, whom Kavanaugh would replace, was a key vote on important tribal issues.

In a statement on its website, NCAI President Jefferson Keel urged tribal leaders to communicate with senators ahead of the confirmation vote to ensure that "tribal sovereignty and treaty rights are honored by the Supreme Court for decades to come."