(1) Unless inconsistent with the ensuing sections of this code defining justifiable use of physical force or with some other provisions of law, conduct which would otherwise constitute an offense is justifiable when it is required or authorized by a provision of law imposing a public duty or by a judicial decree.
(2) The justification afforded by subsection (1) applies when:
(a) The defendant believes his conduct to be required or authorized by the judgment or direction of a competent court or tribunal or in the lawful execution of legal process, notwithstanding lack of jurisdiction of the court or defect in the legal process; or (b) The defendant believes his conduct to be required or authorized to assist a public officer in the performance of his duties, notwithstanding that the officer exceeded his legal authority.