Discipline and Punish

In what instances is it appropriate to rule that an individual's behavior is too far from the mean and therefore needs to be altered? If she is not endangering herself nor anyone else, what is the harm in allowing someone the freedom to believe what and act how she pleases, especially if she is her individuality and uniqueness in doing so? And might it be possible to use reinforcement rather than punishment when trying to fix a particular behavioral problem of a child in school?