Judicial Hubris -- who will judge the judges?

Richard Nadler at NRO has a very sobering article on the horror perpetrated by the Kansas Supreme Court. He includes a quote from the Kansas court which relies on this reasoning from the Kentucky Supreme Court to justify its decision that it has the power and duty to set the level of taxation and spending appropriate for the school system:

…[In this case] we are asked — based solely on the evidence in the record before us — if the present system of common schools in Kentucky is ‘efficient’ in the constitutional sense.… To avoid deciding the case because of ‘legislative discretion,’ ‘legislative function,’ etc., would be a denigration of our own constitutional duty. To allow the General Assembly (or, in point of fact, the Executive) to decide whether its actions are constitutional is literally unthinkable.

Apparently, having judges decide how the executive and legislative branches do their jobs is not unthinkable.

So who judges the judges?