Answer:
They break the laws.
Explanation:
People break the laws and punish the criminals by themselves when they faces injustice because they want justice and decrease the pain they gain from those criminals. First the people go to the courts for availing justice for themselves but when they can't gain justice, they punish the criminals by their own which is against the law but they can't stop themselves due to having the pain given by these criminals. For this type of action of people who want justice, the justice system of the country is responsible.