Final answer:
Both the Civil Rights Movement and Gandhi used nonviolent civil disobedience as a common tactic leading to their imprisonment, which highlighted the legitimacy of their causes against social inequalities and unjust laws.
Step-by-step explanation:
The common tactic involving prison that both the Civil Rights Movement and Gandhi used was the strategy of nonviolent civil disobedience. This form of protest often resulted in the leaders and participants being imprisoned. Figures like Martin Luther King Jr. and Mohandas Gandhi led their respective movements using peaceful protests, sit-ins, marches, and other forms of nonviolent resistance to challenge and draw attention to unjust laws and social inequalities. They both faced arrest and jail time as a consequence of these protests, but their imprisonments served to further highlight the legitimacy of their cause and garner public support.
The imprisonment of these figures made a statement: that the existing laws and practices were so unjust, they were willing to endure incarceration rather than comply. Their respective movements, the struggle for Indian independence and the American civil rights movement, utilized the symbolic power of their leaders' willingness to endure prison to drive home the justice of their efforts for social change.