Discuss (d) actio personalis

The rule: no escape by pleading ignorance of the LAW — the Gazette-publication's fiction that everyone knows the law. The rationale: the contrary rule would make every prosecution turn on unprovable mental states — the law's enforceability requires the fiction. The qualifications (where the marks live): (i) ignorance of FOREIGN law is treated as ignorance of fact; (ii) official misleading interpretations may excuse in defined systems; (iii) where the statute requires knowledge of unlawfulness, ignorance negates the mens rea; (iv) the distinction from mistake of fact (the buffalo thought mine — exculpatory) vs. mistake of law (the buffalo known his, the taking thought lawful — no excuse). Worked pair: A takes B's buffalo believing it his own (mistake of fact — no theft: the dishonest intention negated); A takes B's buffalo knowing it B's, believing the law permits a creditor to seize a debtor's property (mistake of law — the offence stands: ignorantia juris).