Here is the opinion in Flute v. United States.

An excerpt:

This case arises out of an ignominious event in the history of this Nation. In 1864, the United States Army conducted an unprovoked attack on a group of unarmed Indians, who had relocated to an area next to the Sand Creek River in the Territory of Colorado at the direction and under the protection of the Territorial Governor. When what has become known as the Sand Creek Massacre was over, most of the Indians were dead, including many women and children. After an investigation, the United States publicly acknowledged its role in the tragedy and agreed to pay reparations to certain survivors of the massacre. But those reparations were never paid.

Plaintiffs are descendants of the victims of the 1864 Sand Creek Massacre and bring this action for an accounting of the amounts they allege the U.S. government holds in trust for payment of reparations to their ancestors. Because the United States has not waived its sovereign immunity, we affirm the district court’s dismissal of such for lack of subject matter jurisdiction.

Briefs here.