auctoritas: authority, originator, production. From auctor author, promoter, producer, father, progenitor < augēre to make to grow, originate, promote, increase, augment, enlarge, spread, extend
potestas: power, ability, capacity, force. From potis having the power, able, capable, posse to be able, to be possible, to have power, to avail
imperium: a command, order, direction, injunction, supreme authority or power, sovereignty, dominion, the right or power of commanding, authority, command, control. From impero to command, order, enjoin, bid, give an order
These governments are assigned to the Legislature, the Executive, and the Judiciary, in the formal constitutions of American governments.
The Legislature, from which derives and originates all authority of the government, that is the people and the law.
The Executive, which holds substantially all physical and practical power of the state, and implements its force.
The Judiciary, the voice of the sovereign law, which commands the mandamus, so orders the state, and enjoins any party.
We shall see the results of their combination into one.