This article considers the legal structures of the pre-modern common law which ensured that money generally passed at nominal rates in payment transactions. The English sovereign changed the monetary standard many times during the fourteenth to sixteenth centuries so that the purchasing power of the English currency changed markedly at identifiable stages. These changes seem to have left very little trace in the contemporaneous law reports. The article considers why changes in the monetary standard rarely presented a legal issue for common law judges. It argues that English law had a well-defined set of legal structures which ensured that money passed at nominal rates despite a change in the monetary standard. Given the way that payment clauses in common forms of transaction were formulated and actions in debt were pleaded, it would be difficult for a party to raise the change in the monetary standard as an issue for argument in a common law court.