What do you mean by "self-govern on the basis of social reality"?
One which, under the guise of protecting individual rights, elevates judges to super-legislators.
Why would that be tyrannical? It might be somewhat less democratic than what we have now, but it wouldn't confer sole or absolute power on the judiciary, now would that system have to be particularly harsh or cruel.
Tyranny and lack of democracy are not always the same thing, nor is democracy a guaranteed preventive for tyranny.
What I mean by "self-govern on the basis of social reality" is that in a functioning polis under the rule of law, laws are always made that technically restrict individual liberties, but that keep strong beneficial cultural institutions.
For example, legal marriage, with benefits and responsibilities, has been culturally defined as between one man and one woman. Other definitions are imaginable, and may technically afford some legal benefits and symbolic acceptance otherwise unavailable to some. But it is imperative that this legal definition be a legislative not judicial matter. Giving judges the power to willy nilly change the culture is not good. Tyranny? OK, I agree it is not comparable to death squads. Rule by judges is a soft tyranny which to my mind is a significant danger for liberty.