What allowed government officials to restrict the power of other officials of rome?

Roman officers of state could restrict each other's power through the power to veto. Officer of state of the same ranks could veto each other's actions. Officers of state of higher rank could veto the actions of officers of state of lower rank. It was actions which could be vetoed. Only the plebeian tribunes, who were the representatives of the plebeians, but were not officers of state, could veto laws.