A plenary power or plenary authority is a complete and absolute power to take action on a particular issue, with no limitations. It is derived from the Latin term plenus, 'full'.[1]
United States
In United States constitutional law, plenary power is a power that has been granted to a body or person in absolute terms, with no review of or limitations upon the exercise of that power. The assignment of a plenary power to one body divests all other bodies from the right to exercise that power, where not otherwise entitled. Plenary powers are not subject to judicial review in a particular instance or in general
Immigration and nationality
Congress and the President have plenary power to make and enforce immigration and nationality policy, with limited judicial review.[5] This power is rooted in the ideas that immigration and nationality laws are matters of sovereignty; that immigration and naturalization are privileges that exist at the pleasure of a sovereign; and that these laws involve political questions best left to the people.[6] Though this power was largely unused until the 1880s, the ideas underlying it trace as far back as the Roman Empire and were embraced by Founding Fathers such as Gouverneur Morris, who is quoted as stating: "Every society, from a great nation down to a club, had the right of declaring the conditions on which new members should be admitted."[7] The legal basis of this plenary authority lies in the foreign affairs powers under the commerce, naturalization, define and punish, and war clauses of the Constitution.[8][9]
https://en.wikipedia.org/wiki/Plenary_power