After establishing the importance of liberty and individuality in the first part of the book, Mill discusses when a society might rightfully limit individuals and when an individual should maintain sovereignty over themselves. There are some services that an individual in a society owes to that society. For example, people have to serve in common defense of that society. Mill again stresses that society may intervene when a person does harm, however he specifies that in many cases, it is public opinion that should do the policing and correcting, not the law. The law should be involved only where there are violations of rights.

The limits of formal societal intervention stop at the realm of anyone’s personal interests and efforts to control one’s own life. Mill wants people to lift their judgements of others who act in ways that are typically considered unsocial or display behaviors that are uncommon, as long as people acting in these ways are only impacting themselves. People need not agree on the right or best way to act, but they should act in ways that will facilitate their own happiness and help them achieve their personal goals. Individuality remains important in this proscription.