Mistake of law and mistake of fact in English law of restitution

The paper discusses the history of the English law doctrine according to which the mistake of law (error iuris) is a bar for restitution. The author seeks to analyze the premises of mistake that led to recovery of the payment. Since the adjudication of the leading case Bilbie v. Lumley (1802) it was settled by the courts that he who had paid while operating under mistake of fact could demand restitution. On the other hand the one who acted under mistake of law could not. Over the last two centuries, until the ground-breaking decision in Kleinwort Benson Ltd v. Lincoln City Council (1999), the distinction into mistake of law and mistake of fact was very important in cases of undue payment. The author ventures whether there are any foundations for the promotion of the thesis that the aforementioned distinction might be an example of the reception of continental doctrines by the English legal system.