An in-depth study of medieval trade in Europe shows that many important credit-based trades were unpaid. That is why pragmatism and common sense have called for fair compensation for the risk of lending money and compensation for the opportunity costs of lending money without using it for other fruitful purposes. To circumvent the usurban laws enacted by the Church, other forms of reward were created, notably through the widespread form of partnership called commenda, very popular with Italian bankers.  Florentine commercial banks were almost guaranteed to get a positive return on their loans, but this would be before taking into account solvency risks. The United States does not have a federal law that defines the different forms of partnership. .