Joachimson v Swiss Bank Corporation [1921] 3 KB 110 is a judicial decision of the Court of Appeal of England and Wales in relation to the fundamental nature of the legal relationship between banker and customer.

However, the reason the decision is considered so important is for the influential comments made by way of obiter dictum by Atkin LJ in relation to the nature of the banker-customer relationship.

The firm's account with the bank was dormant for the duration of the war; the case report suggests that this might have been because of legal prohibitions relating to property of enemy aliens.

Bankes LJ held:[7] It seems to me impossible to imagine the relation between banker and customer, as it exists today, without the stipulation that, if the customer seeks to withdraw his loan, he must make application to the banker for it...The case is treated as important because of the fundamental principles which Atkin LJ set down in relation to the nature of the account.

Ellinger's Modern Banking Law[1] suggests that, taken together with Foley v Hill, the case established six fundamental propositions: Some care needs to be taken with the last proposition: much of English law at the time was expressed in terms of "implied agreements" and "quasi contract"; a position which academics have pointed out should be deprecated and recognised that the courts were simply laying down legal rules and not implied agreements.