The Justice Bloc was the largest of the many voting blocs of Vault 11, seeking to influence the votes of fellow vault dwellers. During the last overseer election, the Justice Bloc threatened to nominate Nathan Stone, husband of Katherine Stone, for overseer if she wouldn't perform sexual favors for their members. It is hinted that their anger at Nathan Stone originated from his unusual winning streaks during poker games. Despite Katherine complying, the Justice Bloc nominated Nathan anyway. Typically, since the nominees were those who were in notoriety to the community, they would be backed by multiple blocs. However, Nathan's nomination was backed only by the Justice Bloc. Fearing for her husband, Katherine began to take matters into her own hands and began stalking and killing members of the Justice Bloc. Eventually, she was caught. Katherine confessed to her crimes immediately and beyond explaining her motives, she said that by being a serial killer, she would no doubt be elected as overseer so she could terminate the power and influence of the Justice Bloc. Her first act, "Overseer Order 745", decreed that the sacrifice would no longer be the elected overseer, but rather a random member of the vault selected by computer lottery.
The Justice Bloc, in anger at their loss of power and in fear of the possibility that one of their members might be selected, staged a violent coup against the Overseer. The fighting rapidly spread out of control, leading to the deaths of everyone in the Vault but five people. Of these survivors, as told by an audio log, four committed suicide with the last survivor's fate unknown.
The Justice Bloc is only mentioned in Fallout: New Vegas.