Ethicist: An action is wrong if it violates a rule of the society in which the action is performed and that rule promotes the general welfare of people in the society
An action is right if it is required by a rule of the society in which the action is performed and the rule promotes the general welfare of the people in that society
Amelia's society has a rule against lying. However, she lies anyway in order to protect an innocent person from being harmed. While the rule against lying promotes the general welfare of people in the society, Amelia's lie is not wrong because she is preventing harm.