Consider William Rehnquist: a once-brilliant man, now 81 years old, infirm, possibly dying of thyroid cancer, likely on pain medication which will still further dull his fading faculties. Yet he clings to "power" -- to the extent that it can still be called his.
Now, consider William Rehnquist's senior clerks. Probably in their thirties, probably brilliant, certainly powerful beyond all their expectations. They now have, for practical purposes, most of the power nominally vested in their senile figurehead. And I conjecture that they cling to it as well, murmuring encouragement and flattery to strengthen a fading man's fading resolve.
People say Justices are unaccountable; how much more so, though, are the faceless functionaries who now hold the reins.