“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 terms of St. Thomas Aquinas: An unjust law is a human law that is not rooted in eternal law and natural law. Any law that uplifts the human personality is just. Any law that degrades human personality is unjust. All segregation statutes are unjust because segregation distorts the soul and damages the personality. It gives the segregator a false sense of superiority and the segregated a false sense of inferiority.”

On Free Choice Of The Will, Book 1, § 5

Source: Bibelausgaben, Die Bibel nach der Übersetzung Martin Luthers, mit Apokryphen, Neue Rechtschreibung, Schwarz

Source: Cry, the Beloved Country

1960s, Letter from a Birmingham Jail (1963)
Source: Letter from the Birmingham Jail
Context: One may well ask: "How can you advocate breaking some laws and obeying others?" The answer lies in the fact that 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."

1960s, (1963)

From "In Defense of Self-defense" I (June 20, 1967)
To Die For The People
Context: Men were not created in order to obey laws. Laws are created to obey men. They are established by men and should serve men. The laws and rules which officials inflict upon poor people prevent them from functioning harmoniously in society. There is no disagreements about this function of law in any circle-the disagreement arises from the question of which men laws are to serve. Such lawmakers ignore the fact that it is the duty of the poor and unrepresented to construct rules and laws that serve their interest better. Rewriting unjust laws is a basic human right and fundamental obligation.

Guerilla Open Access Manifesto (July 2008) http://archive.org/details/GuerillaOpenAccessManifesto.
Context: There is no justice in following unjust laws. It’s time to come into the light and, in the grand tradition of civil disobedience, declare our opposition to this private theft of public culture.
We need to take information, wherever it is stored, make our copies and share them with the world. We need to take stuff that's out of copyright and add it to the archive. We need to buy secret databases and put them on the Web. We need to download scientific journals and upload them to file sharing networks. We need to fight for Guerilla Open Access.
With enough of us, around the world, we’ll not just send a strong message opposing the privatization of knowledge — we’ll make it a thing of the past. Will you join us?

Non-Violence in Peace & War (1962) Vol. 2, edited by Mahadev Haribhai Desai, p. 144
Posthumous publications (1950s and later)
Context: An unjust law is itself a species of violence. Arrest for its breach is more so. Now the law of nonviolence says that violence should be resisted not by counter-violence but by nonviolence. This I do by breaking the law and by peacefully submitting to arrest and imprisonment.