This work offers some solutions to issues faced by domestic courts and arbitral tribunals when one party to a sales contract withholds performance on the ground that a trade sanction prohibits the transaction. The discussion sheds light on the authority of arbitrators to give effect to statutes serving public interests, and shows that the architecture of trade sanctions protects them from being easily dismissed. Even if a given sanction does not constitute a legal impediment justifying the defaulting party's exemption from liability, the risk of penalty that this party would incur if it were to perform the contract in breach of the sanction may justify an adaptation of the contract. The heavier the penalties and the longer a sanction's term, the more efficient the sanction, if not in achieving its ultimate political goal, certainly in preventing the performance of contracts under the initially agreed terms.