The "Letter from Birmingham Jail", also known as the "Letter from Birmingham City Jail" and "The Negro Is Your Brother", is an open letter written on April 16, 1963, by Martin Luther King Jr. It says that people have a moral responsibility to break unjust laws and to take direct action rather than waiting potentially forever for justice to come through the courts. Responding to being referred to as an "outsider", King writes: "Injustice anywhere is a threat to justice everywhere."

Martin Luther King Jr. was an American Christian minister, activist, and political philosopher who was one of the most prominent leaders in the civil rights movement from 1955 until his assassination in 1968. A black church leader and a son of early civil rights activist and minister Martin Luther King Sr., King advanced civil rights for people of color in the United States through the use of nonviolent resistance and nonviolent civil disobedience against Jim Crow laws and other forms of legalized discrimination.