Actually to parent's point, it's ensuring that even if the worst people got into positions of power, things would be structured enough and there'd be enough checks to keep them from doing any real damage.
This is one of those things that sounds nice but is mostly self-contradictory (or, at least, requires magic) -- if there is something checking to prevent "the worst people" from doing real damage in "positions of power", then:
1) The positions you are atalking about really don't have all that much power, and
2) Assuming that the checks aren't magical external impersoal forces, the people doing the checking actually exert the real power.
