It was a substantive requirement that the United States government had agreed to as a condition of the treaty.

The gap between the language and what happened is total.

Within six years of signing the treaty, the United States had sent a military expedition — in violation of the “undisturbed” promise — into the Black Hills.

Within nine years, it had enacted legislation that stripped the Black Hills from the reservation without obtaining the three-fourths approval the treaty required.

The Supreme Court found this gap sufficiently clear and documented to constitute a cognizable taking under the Fifth Amendment.

The Court’s finding implicitly acknowledged what the language of the treaty itself makes clear: the United States had made specific, binding promises and had broken them in specific, documented ways.