In these examples, when should "Tribe" or "Tribal" be capitalized?
"This rulemaking will preempt State, local, and Tribal requirements but does not propose any regulation that has substantial direct effects on the States, the relationship between the national government and the States, or the distribution of power and responsibilities among the various levels of government."
"The Federal hazmat law contains an express preemption provision [49 U.S.C. 5125 (b)] that preempts State, local, and Indian Tribal requirements on the following subjects:"
My assumption is that because they aren't proper nouns, they shouldn't be capitalized.
Best Answer
It appears (from a comment) that you're asking about the US Government Publishing Office style guidelines.
It appears that according to the 2016 edition of the GPO Style Manual, tribe and tribal should always be capitalized when they refer to federally recognized American Indian tribes.
So it would be: "Many members of the Suquamnish Tribe live on the Port Madison Reservation. The Tribal leaders work on projects that provide cultural, educational, and recreational resources for the community. The Tribe has 890 enrolled members."
But: "The survivors of the shipwreck formed two tribes."
And: "The tribal delegation from Greenland arrived yesterday."
(emphasis added)
This is somewhat counter-intuitive, both because it's different from many other guidelines and because it doesn't seem to fit a consistent pattern within the GPO guidelines.
For example, we're told to always capitalize Navy, but naval is not capitalized. You'd think that the same rule might apply to Tribe and tribal.