Aquinas on Unjust Laws

Reply Obj. 2. Human law has the nature of law in so far as it partakes of right reason; and it is clear that, in this respect, it is derived from the eternal law. But in so far as it deviates from reason, it is called an unjust law, and has nature, not of law but of violence. Nevertheless, even an unjust law, in so far as it retains some appearance of law, though being framed by one who is in power, is derived from the eternal law; since all power is from the Lord God, according to Rom. 13:1.

Reply Obj. 3. Human law is said to permit certain things, not as approving of them, but as being unable to direct them. And many things are directed by the Divine law, which human law is unable to direct because more things are subject to a higher than to a lower cause. Hence the very fact that human law does not meddle with matters it cannot direct, comes under the ordination of the eternal law. It would be different, were in human law to sanction what the eternal law condemns. Consequently, it does not follow that human law is not derived from the eternal law, but that it is not on a perfect equality with it.

Thomas Aquinas. Summa Theologica. Trans. Fathers of the English Dominican Province. London: Burns Oates & Washbourne. Print.,,