the.com/checks and balances

means A system that splits power across different branches of government so each one can limit the others and no single authority can seize total control.

from The idea traces to Enlightenment political theory, especially the French thinker Montesquieu, who argued that liberty survives only when legislative, executive, and judicial power are separated and set against one another. The phrase itself echoes older, literal uses of 'checks' (a check as something that restrains or stops, like a check on a horse's reins) and 'balances' (as in a weighing scale, where opposing weights keep things level). American framers absorbed this thinking directly, building the US Constitution around the three branches so each could check the others' excesses — the phrase 'checks and balances' became the shorthand for that architecture.