A significant motif in Twelve Angry Men is that of leadership. Although Juror #9 is not the appointed leader, he assumes the role of leader through his actions, engaging others, persuading, and negotiating.
The appointed leader of the group organizes and plans the meeting. However, Juror #9 took leadership to the next level. He demonstrated how someone can be a leader even without being designated the leader.
He convinced the other jurors that they should consider the boy's guilt or innocence based on the facts. Further, he encouraged them to look at the facts with new eyes. He did so by engaging them in replaying the murder, persuading them of his ideas and negotiating with the othe jurors when they wanted to lead early.