1) Requirement to perform some conduct required by law, custom, morality, or personal commitment. This requirement often created a right in the other that the duty be performed, and a breach of such duty (ex. Fiduciary duty, duty of good faith, duty of care, duty of loyalty etc.) gives rise to a cause of action for violation of the right. However, there are some duties in law (ex. Duty of public officials) that do not give right to an action.
2) A tax on imported goods.
[Last updated in June of 2020 by the Wex Definitions Team]