Native American Graves Protection and Repatriation Act (NAGPRA) is a Congressional Act signed into law in 1990. The law is an attempt to provide a way for native people to accomplish several things including: 1) protection of holy sites and religious burials from development and construction activities 2) the return to proper tribes of Native American bones and artifacts stolen from them over the last 500 years, including property held by museums and universities, and 3) providing more independent oversight of construction or land development sites on Indian Territory.
While in general this bill has been long overdue, and is a building block of better relations with Indian people and the US Government, it has some de facto problems.
- At what point are ancient bones of "anthropological" interest in general, and at what point are they truly bones of a given tribe? 500 year old bones? 1000 year old bones? 10,000 year old bones? If a bone were found in the US, to be 1,500,000 years old, and show evidence of Alien presence, is that still a "Native American" bone? 
- Which tribe gets to say if a location can be disturbed, or of the location under construction is a religious site?
- What happens when 2 or more tribes demand access to bones and artifacts.
Like most modern human endeavors, much of this law provides quality redress of centuries of mistreatment; however, amoral lawyers, Indian leaders, and political figures can and do abuse the law for profit or power.
- See Kennewick Man controversy and the small role NAGPRA played in the situation
- Though this example is extreme, the fact is that the law itself makes no clear distinction between bones that would clearly be the legacy of a particular tribe, and those old enough to simply be something more generally "human interest".