I have worked with the Native American's in doing environmental documents and there is a unique situation where working with the tribes. Since they are considered a sovereign nation, they actually do not have to comply with the National environmental regulations because they are not of this nation. They actually choose to do it as a kind of sign of friendliness to neighboring nation. When I was writing a document for them, I found a word that described that but I have lost it. I have asked a few lawyers that with Tribal activities and cannot get the help I need. Any help out there?
The only word that comes to my head just now is "accord", but I don't think that's what you're looking for. Can you use it in a sentence? That is, would you use it "as a sign of [?] between nations", or "the Cherokee nation [?]ed the United States in this matter", or "three nations signed a [?] agreeing that they would..." or what?