Final answer:
The Northwest Ordinance Act assured that the US wouldn't take new lands without Native American consent, except during just wars authorized by Congress.
Step-by-step explanation:
The Northwest Ordinance Act promised that the US would not take any new lands without the consent of Native Americans. The 1787 legislation aimed at the settlement of the Northwest Territory stated that the utmost good faith shall always be observed towards the Indians; their lands and property shall never be taken from them without their consent, except in just and lawful wars authorized by Congress. This ordinance set a precedent for how the government would approach the acquisition of new lands, acknowledging the rights of Native Americans.