False pretence of office

Every person who pretends to be or acts as a public officer or juror, not being lawfully authorised to act as such officer or juror, is guilty of a misdemeanour, unless he shows either– (a) that he so pretended or acted under a mistake of law or of fact; or (b) in the case of a person acting as a public officer, that he so acted in good faith for the public benefit.