When President Obama held the eighth White House Tribal Nations Conference last fall, all 567 federally recognized tribes were invited to attend. As the Standing Rock demonstration continued in North Dakota, participants talked about a variety of issues, including how the United States could more carefully consider indigenous rights and property when planning and permitting future infrastructure projects.

But not all indigenous peoples were represented at the president's home. Invitations were extended only to leaders of federally recognized tribes. As many as 50 tribes, representing tens of thousands of people, were not part of the event because the United States disputes, denies, or has yet to make a decision on their petition for federal acknowledgement. As the Standing Rock Sioux have fought to assert their federal rights as indigenous people, other tribes remain in the shadows, struggling to be recognized as Native communities in the first place.

For citizens of these communities, a positive determination could have life-changing consequences. Members of recognized tribes can receive federal support for housing, education, and health care, which the US government is legally obligated to provide tribes in accordance with negotiated treaties and federal statute.

These benefits, however, are less consequential than the legal authority obtained by recognized tribes, according to Arlinda Locklear, an expert in Native American law based in Washington DC, and the first Native American woman to argue before the US Supreme Court.

"A federally recognized tribe is a government. It's not a racial classification," she explains. "It's a political classification." In other words, recognition allows a tribe's "cultural and social mores [to] become the lodestar" for their political organization. For example, recognized tribes may regulate commerce, such as licensing the operation of a casino or hotel, and enforce tribal laws, according to their societal norms, on lands they own.