A human law has the character of law to the extent that it accords with right reason, and thus derives from the eternal law. Insofar as it falls short of right reason it is said to be an unjust law, and thus has not so much the nature of law as of a kind of violence. 22
Catechism number 1904
"It is preferable that each power be balanced by other powers and by other spheres of responsibility which keep it within proper bounds. This is the principle of the 'rule of law,' in which the law is sovereign and not the arbitrary will of men."