Answer:
Utilitarianism's primary weakness has to do with justice. Utilitarianism seems to require punishing the innocent in certain circumstances, such as these. It is wrong to punish an innocent person, because it violates his rights and is unjust. But for the utilitarian, all that matters is the net gain of happiness.
Step-by-step explanation:
As a theory of justice, utilitarianism holds that all human actions (as well as those of a state) are virtuous, moral, and just when they contribute to achieving general happiness. Hence, actions are judged based on their consequences. Actions detrimental to general happiness are considered unjust.