When is a law an unjust law?

When is a law an unjust law?

Yesterday, Kim Davis, a county clerk in Kentucky, was sent to jail for refusing to issue marriage licenses to same-sex couples. This set off a flurry of commentary on the Interwebs, with most proponents of same-sex marriage claiming that it was an issue of the law. For example:

To which I argued:  

Of course, I was attacked for comparing Martin Luther King’s fight for civil rights with those who oppose same-sex marriage, but my point was broader: there is such a thing as an “unjust law”, and just about everyone recognizes this. In fact, progressives haven’t always been so gung-ho for the “rule of law:”

So what makes a law “unjust”? How do we determine this? I think MLK, basing himself on St. Augustine, St. Thomas Aquinas, and the Christian tradition, says it very well in his “Letter from a Birmingham Jail” (emphasis added):

There are two types of laws: just and unjust. I would be the first to advocate obeying just laws. One has not only a legal but a moral responsibility to obey just laws. Conversely, one has a moral responsibility to disobey unjust laws. I would agree with St. Augustine that “an unjust law is no law at all.”

Now, what is the difference between the two? How does one determine whether a law is just or unjust? A just law is a man made code that squares with the moral law or the law of God. An unjust law is a code that is out of harmony with the moral law. To put it in the terms of St. Thomas Aquinas: An unjust law is a human law that is not rooted in eternal law and natural law.

“Not rooted in eternal law and natural law” – that is the key to determining if a human law is just or unjust. In the case of segregation, the laws in this country were unjust because they went against the dignity of the human person, considering one race of people inferior to others. In the case of same-sex marriage, the laws in this country are unjust because they go against the dignity of marriage as it has been understood throughout human history: a union of a man and a woman. Thus, Kim Davis is acting squarely in the tradition of MLK by refusing to issue marriage licenses to those who simply cannot, by natural law, contract a marriage.