When Parks refused to give up her seat, a police officer arrested her. As the officer took her away, she recalled that she asked, "Why do you push us around?" She remembered him saying, "I don't know, but the law's the law, and you're under arrest." She later said, "I only knew that, as I was being arrested, that it was the very last time that I would ever ride in humiliation of this kind. ... ". Parks was charged with a violation of Chapter 6, Section 11 segregation law of the Montgomery City code, although technically she had not taken a white-only seat; she had been in a colored section. Edgar Nixon, president of the Montgomery chapter of the NAACP and leader of the Pullman Porters Union, and her friend Clifford Durr bailed Parks out of jail that evening.
On Sunday, December 4, 1955, plans for the Montgomery bus boycott were announced at black churches in the area, and a front-page article in the Montgomery Advertiser helped spread the word. At a church rally that night, those attending agreed unanimously to continue the boycott until they were treated with the level of courtesy they expected, until black drivers were hired, and until seating in the middle of the bus was handled on a first-come basis.
The next day, Parks was tried on charges of disorderly conduct and violating a local ordinance. The trial lasted 30 minutes. After being found guilty and fined $10, plus $4 in court costs, Parks appealed her conviction and formally challenged the legality of racial segregation.
That Monday night, 50 leaders of the African-American community gathered to discuss actions to respond to Parks' arrest. Edgar Nixon, the president of the NAACP, said, "My God, look what segregation has put in my hands!" Parks was considered the ideal plaintiff for a test case against city and state segregation laws, as she was seen as a responsible, mature woman with a good reputation.
After the success of the one-day boycott, a group of 16 to 18 people gathered at the Mt. Zion AME Zion Church to discuss boycott strategies. At that time Parks was introduced but not asked to speak, despite a standing ovation and calls from the crowd for her to speak; when she asked if she should say something, the reply was, "Why, you've said enough." The group agreed that a new organization was needed to lead the boycott effort if it were to continue. Rev. Ralph Abernathy suggested the name "Montgomery Improvement Association" (MIA). The name was adopted, and the MIA was formed. Its members elected as their president Martin Luther King, Jr., a relative newcomer to Montgomery, who was a young and mostly unknown minister of the Dexter Avenue Baptist Church.