“In principle and on authority it seems to me that the court should not, save in exceptional circumstances, impose such a requirement upon a foreigner, and, in particular, upon a foreign bank. The principle is that a state should refrain from demanding obedience to its sovereign authority by foreigners in respect of their conduct outside the jurisdiction… (493G) The need to exercise the court's jurisdiction with due regard to the sovereignty of others is particularly important in the case of banks. Banks are in a special position because their documents are concerned not only with their own business but with that of their customers. They will owe their customers a duty of confidence regulated by the law of the country where the account is kept… (494B-D) International law generally recognises the right of a state to regulate the conduct of its own nationals even outside its jurisdiction, provided that this does not involve disobedience to the local law. But banks, as I have already said, are in a special position. The nature of banking business is such that if an English court invokes its jurisdiction even over an English bank in respect of an account at a branch abroad, there is a strong likelihood of conflict with the bank's duties to its customer under the local law. It is therefore not surprising that any bank, whether English or foreign, should as a general rule be entitled to the protection of an order of the foreign court before it is required to disclose documents kept at a branch or head office abroad… (496) It seems to me that in a case like this, where alternative legitimate procedures are available, an infringement of sovereignty can seldom be justified except perhaps on the grounds of urgent necessity… (499F)”
“The point is also recognised in judicial authority. In Jeremy Stone Consultants Ltd v National Westminster Bank plc[2013] EWHC 208 (Ch) Sales J addressed a claim to recover from the defendant bank money which it was induced by a third party to pay into a company's bank accounts when the company, unbeknown to the claimants, was part of the third party's fraudulent Ponzi scheme. One of the claims against the bank was for restitution of the moneys in those accounts on the basis of NatWest's unjust enrichment as a result of the moneys having been paid on the basis of a mistake. Sales J rejected the claim based on unjust enrichment on two grounds. First, he held that the defendant bank had not been enriched. He stated (para 242): “it is true that when the claimants paid sums to NatWest for the account of SEWL, NatWest received those sums and added them to its stock of assets as moneys to which it was beneficially entitled. However, the increase in its assets was matched by an immediate balancing liability, in the form of the debt which NatWest owed SEWL reflected in the increase in SEWL's bank balance as a result of the payments.”
“Secondly, even if there had been enrichment, he held that the bank had a defence of good faith change of position and a defence of ministerial receipt, because it had a contractual obligation to pay out the sums in SEWL's account in accordance with its customer's instructions and had done so.”