Injustice anywhere is a threat to justice everywhere... 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." - Martin Luther King Jr., "Letter from a Birmingham Jail" (April 16, 1963)
…one of the great problems of history is that “the concepts of love and power have usually been contrasted as opposites, polar opposites, so that love is identified with a resignation of power, and power with a denial of love. What is needed is a realization that power without love is reckless and abusive, and that love without power is sentimental and anemic. Power at its best is love implementing the demands of justice, and justice at its best is love correcting everything that stands against love. MLK 1967
"Now is the time to make justice a reality for all of God's children. ... No, no, we are not satisfied, and we will not be satisfied until "justice rolls down like waters, and righteousness like a mighty stream." Martin Luther King, Jr.
"Every step toward the goal of justice requires sacrifice, suffering, and struggle; the tireless exertions and passionate concern of dedicated individuals." - Martin Luther King, Jr.
“The arc of the moral universe is long, but it bends towards justice.” MLK
"First, I must confess that over the past few years I have been gravely disappointed with the white moderate. I have almost reached the regrettable conclusion that the Negro's great stumbling block in his stride toward freedom is not the White Citizen's Counciler or the Ku Klux Klanner, but the white moderate, who is more devoted to "order" than to justice; who prefers a negative peace which is the absence of tension to a positive peace which is the presence of justice; who constantly says: "I agree with you in the goal you seek, but I cannot agree with your methods of direct action"; who paternalistically believes he can set the timetable for another man's freedom; who lives by a mythical concept of time and who constantly advises the Negro to wait for a "more convenient season." Shallow understanding from people of good will is more frustrating than absolute misunderstanding from people of ill will. Lukewarm acceptance is much more bewildering than outright rejection."
MLK — Letter From a Birmingham Jail, 1963 
3. "But it is not enough for me to stand before you tonight and condemn riots. It would be morally irresponsible for me to do that without, at the same time, condemning the contingent, intolerable conditions that exist in our society. These conditions are the things that cause individuals to feel that they have no other alternative than to engage in violent rebellions to get attention. And I must say tonight that a riot is the language of the unheard. And what is it America has failed to hear?...It has failed to hear that the promises of freedom and justice have not been met. And it has failed to hear that large segments of white society are more concerned about tranquility and the status quo than about justice and humanity." MLK — “The Other America,” 1968 [8