What did rulers do in attempts to aid each other in case of revolution?

Offer military aid, such as expeditionary troops, and in case of the country being unsafe, a flight to theirs.

worcester v. georgia, legal case in which the u.s. supreme court on march 3, 1832, held (5–1) that the states did not have the right to impose regulations on native american land. andrew jackson refused to enforce the ruling, the decision form the basis for most subsequent indian law in the united states.

protect u.s. businesses from competition