Morality has to do generally with right and wrong. Wrongs are essentially subject to punishment of some form. Thus, any violation of law, any injustice, is a wrong subject to penal sanction. But this does not distinguish the matter of justice from morality more generally. Is there something unique about justice in contrast to morality, as seems to be the case.
Duties are essential to the idea of morality.
Those who fail to do what moral obligation requires of them may be compelled to do so or, in the event of failure to comply, they are subject to punishment. Duty is a kind of indebtedness. This is what, in the end, distinguishes morality from expediency. An advisor can highly recommend, or try to persuade or admonish, without being in a position to require on the grounds that the advisee has an obligation to comply. There is an appeal to the advisee's own good, whereas what one owes on grounds of morality is independent of the condition of one's own interest and excludes it as a reason for action.