The rule in Ralli Bros will excuse non-performance of an English law obligation where performance necessarily involves an act prohibited by the law of the place of performance. However, the courts have not given clear guidance on identifying the place of performance where a foreign bank plays an ancillary role in the performance of such an obligation. While there is good reason to consider that payment of liabilities in a foreign currency, or to a foreign account, necessarily involves performance in a foreign country, each contract or instrument must be carefully examined to determine what precise acts fall to be performed, and where.