Legal Case Summary
R v King [1964] 1 QB 285
Mistake on the facts as a defence to a charge of bigamy under Offences Against the Person Act 1861
Facts
The defendant had remarried while his previous marriage was still valid. He was prosecuted for bigamy contrary to section 57 of the Offences Against the Person Act 1861, which states that:
“Whosoever, being married, shall marry any other person during the life of the former husband or wife, whether the second marriage shall have taken place in England or Ireland or elsewhere, shall be guilty of felony…” (OAPA 1861, s.57).
His argument had been that he had entered into the new marriage under the honest mistaken belief that his previous marriage was void.
Issues
Whether a genuine mistaken belief as to a fact is a defence to a charge of bigamy under s.57 OAPA 1861.
Decision / Outcome
Mistake can be used successfully as a defence in this context only where the belief is not only honest, but also reasonable – this would negate the mens rea requirement of s.57 OAPA 1861. The court distinguished R v. Wheat & Stocks[1921] 2 K.B 119where even a reasonable belief was not held to be sufficient for a defence (that case was in any event overruled byR v. Gould [1968] 2 Q.B 65 which further entrenched the rule that honest and reasonable belief could amount to a defence to a charge of bigamy). An unreasonable belief does not suffice, inter alia, because it betrays negligence as to the facts on which the belief is based.
Updated 20 March 2026
This case summary remains broadly accurate. R v King [1964] 1 QB 285 is still correctly cited for the proposition that an honest and reasonable mistake of fact may negative the mens rea required for bigamy under section 57 of the Offences Against the Person Act 1861. The subsequent case of R v Gould [1968] 2 QB 65, which confirmed and extended this principle, is also correctly noted.
One point worth clarifying for students: section 57 of the Offences Against the Person Act 1861 remains in force, though the classification of bigamy as a ‘felony’ is no longer meaningful following the abolition of the distinction between felonies and misdemeanours by the Criminal Law Act 1967. Bigamy is now simply an indictable offence. This does not affect the substantive legal principles discussed in the article.
Students should also be aware that the broader question of how mistake of fact operates as a defence in English criminal law was significantly developed in later cases such as DPP v Morgan [1976] AC 182, where the House of Lords held that in some contexts an honest (but not necessarily reasonable) belief may suffice. However, bigamy under section 57 OAPA 1861 remains an exception where reasonableness of the belief is required, as confirmed by R v Gould. The article’s summary of the law on bigamy specifically is therefore still accurate.
