The US practice of the extraterritorial application of sanctions was criticised for years as, at best, the illegitimate abuse of its particular position in the world’s economy. Despite its fully comparable position in international finance, the United Kingdom was shielded from such criticism predominantly thanks to the transfer of respective decision-making to Brussels. The nature and scope of sanctions were delineated by EU laws. As the UK prepares its (financial) sanctions regime for Brexit, could it draw criticism similar to the US for both giving too broad discretionary powers to the government and preventing it from meeting UK international obligations at the same time? I suggest the new regime for the extraterritorial application of sanctions possibly opens the UK to international liability for, both, the lack of a legal basis for a legal restriction upon states as well as inevitable omissions to prevent gross violations of international law.
Since analysis of legal sanctions under international law is a very complex, multi-stage exercise, I focused on relatively easier cases of discretionary goals of foreign policy and extraterritorial sanctions, where the legal threshold for an internationally wrongful act is lower. Accordingly, I highlight the normative basis for adopting financial sanctions against third-state persons not covered by exceptions, British BITs, or the most relevant multilateral treaties. As for possible breaches of international law by omission, I focus on tolerating the provision of financial services contributing towards gross violations of international law. Because of length limitations, I do not discuss anti-money laundering per se, which is subject to yet another chapter of the law in question.