This essay analyses the decisions of the United States Supreme Court on the allocation of the burden of proof in relation to criminal defences. The Court seems generally comfortable about letting the accused carry the persuasive burden of proving excuses and justifications. It is seemingly different in those other common law countries where the so-called ‘golden thread’ proclaimed by the House of Lords in Woolmington v DPP holds sway, and where it is accepted as a general rule that the prosecution must disprove beyond reasonable doubt any defence that has been put in issue. This essay explores and tries to explain this difference. The divergence is explicable as a matter of legal history, but at the bottom of it are arguably a conceptual dispute on the offence-defence distinction and competing visions of politics that bear on the theory of the criminal trial.