Literally nothing in the legal system is permanent for perpetuity. Even the constitution can be amended in any way. All laws, treaties, etc. can be undone with enough effort.

Not quite. It is, in theory, possible to pass an amendment to the constitution, that would prohibit further amendments to parts of it. Quite a few countries have such "immutable clauses" in their constitutions.

Those countries can just make new constitutions. There is literally nothing stopping them.

Well, yes, but that's just a fact of legislation. There are no "promises"; there are just laws that are easy or hard to change. If we were to amend the constitution to set aside land for native peoples, then that's probably the closest we can get to a promise, as that's probably the hardest kind of law to change -- but it's still not a promise, because it can be changed.

Sure, Congressional legislation could take away that land. That would be a lousy thing for them to do. Unfortunately since I doubt Native American groups are a big enough voting bloc, the only thing that would stop Congress from doing that would be enough negative public opinion from people who are not Native American. Hopefully there are enough people of that sort.

The Russian Duma could revoke the sale of Alaska to the United States and declare that they still own it. What stops them from doing so? The fact that the US military would stop them from trying to repossess the land.

The "promise" to the Creek isn't worth the paper it's written on because they don't have enough military might to enforce the terms of the agreement. The US operates with them as it does with every one else, on the principle of "might makes right."

> The "promise" to the Creek isn't worth the paper it's written on because they don't have enough military might to enforce the terms of the agreement.

This is patently false, because the Supreme Court has ruled that the promise is enforceable.

> The US operates with them as it does with every one else, on the principle of "might makes right."

This is also completely false. Does the military answer to the President of the US because "might makes right"? Can Trump overpower any enlisted man in the military with a gun? The military obeys the Constitution because they swore an oath to do so, not because the generals have literal guns to their heads.

Culture and rule of law matter. The statement "might makes right" is a gross oversimplification that doesn't reflect our reality at all.

The Supreme Court has merely ruled that Congress must first tear up the paper before violating the promise written on it.

The court is highlighting that congress needs to be consistent. Make a willing refusal to original promise, otherwise keep said promise. The courts job is not to decide on the promise but to identify the congress as responsible for consistency with promises made.

I’m curious if you can give an example of a promise that cannot ever be revoked?

I mean, the only reason that Congress can revoke a promise to the Creek Indians is that they have a stronger military. It's not about justice, it's just about strength.

I expect someday Congress with revoke the promise of a social security check, when the system can no longer stand on its own.

If and when the United States Treasury stops honoring bonds that it sells, then you'll have bigger problems than whether or not you get social security income.

It’s a good question — if anything I’d think that a promise is revocable by definition. If there’s no trust involved it’s not so much a promise as...collateral, or something?