Out of the three branches of government, the legislature is often considered to be "first among equals." What does this mean?
If it means that any positive law overrides any natural law, then clearly, the legislature would by that very fact neuter the judicial branch. No judge would have the power to disqualify as unjust even the most atrocious bill, such as one that commands all Jews to report to gas ovens.
And of course, if vice versa, then it is judges who would be made into tyrants.
What is to be done?
One attempted solution is the American system of federal government. The Constitution defines a government by enumerating its powers and promulgates an elite-made natural-law system.
It codifies, as the best minds of the time figured it, several fundamental principles of justice that serve as law of the land.
Within that system, the legislature is made supreme, and judges are not allowed to override Congressional statutes, however immoral. At the same time, no bill may contradict the Constitution. As long as that happens, a Congressional action is allowed to prevail over any judicial tradition. So, the Congress works under the Constitution but over judges.
Another solution may be discerned by studying the British system. The House of Lords is -- or was until recently -- an equivalent of the Supreme Court. A working system would then be to prevent any bill from passing until it is approved both by the legislature proper -- the House of Commons -- and by the chief judges -- the members of the House of Lords.
In this case, a law that clears both Houses acquires the dual status of both efficient (from Commons) and just (from Lords). Here the two branches are fully equal.
Under a functioning monarchy, the king would also have to consent to a law if it is to be passed, though on what grounds this power would belong to him I do not understand at this moment.