Final answer:
Items not subject to repatriation under NAGPRA include those with unclear provenance or those located internationally, as NAGPRA applies only to the U.S. Repatriation issues also arise when tribal affiliation cannot be determined as per the law's guidelines.
Step-by-step explanation:
Under the Native American Graves Protection and Repatriation Act (NAGPRA), items that are not subject to repatriation include those that lack a clear provenance, meaning they cannot be definitively linked to a specific tribe or culture. This can make it impossible to return an object or human remains to the original tribe. Furthermore, NAGPRA does not apply internationally, so ancestral human remains and sacred objects in museums outside of the United States are not subject to the rules and protections offered by this U.S. law. Issues with tribal affiliation can also arise, making it difficult to repatriate to groups whose relationship to the items cannot be clearly defined within the law's terms.
Since its enactment, NAGPRA has provided for the repatriation of cultural items, funerary objects, sacred objects, and human remains, but there are still many remains and cultural items held by institutions both within the U.S. and internationally that fall outside of its scope. The need for an international version of NAGPRA is highlighted by the fact that museums and collections around the world hold items that the original communities value deeply and believe are in need of repatriation. These challenges underscore the ongoing struggle to correct historical injustices and to respect the rights of indigenous cultures to their ancestors' remains and cultural heritage.