On August 27, 1996, less than a month after Will Thomas pulled a skull from the Columbia River, five Native American tribes filed a formal claim for the remains under a federal law called the Native American Graves Protection and Repatriation Act.

NAGPRA, as it’s universally known, was passed by Congress in 1990 — just six years before Kennewick Man’s discovery.

It was, and remains, one of the most important pieces of legislation in the history of Native American rights.

Before NAGPRA, museums and research institutions across the country held thousands — in some estimates, hundreds of thousands — of Native American skeletal remains and sacred objects, collected over a century of archaeological excavation, often without tribal consent and sometimes in direct violation of tribal burial practices and religious beliefs.

The remains of Native people had been dug up, measured, catalogued, shipped to institutions across the country, stored in boxes in basements, and treated as scientific specimens rather than as the human beings they were.

NAGPRA changed this.

The law required federally funded institutions to inventory their Native American collections and consult with tribes about the return of affiliated remains and objects.

It established a process for repatriation — the formal return of remains and sacred items to the communities they belonged to.

The key word in NAGPRA is “affiliated.” The law requires a demonstrable cultural affiliation — a connection, established through a preponderance of evidence, between the remains in question and a present-day tribal community.

The five tribes who filed the 1996 claim — the Umatilla, the Yakama, the Nez Perce, the Colville, and the Wanapum — argued that this connection was clear.