What are the Legal perspectives on withholding access to banking facilities and financial networks from both

clients and banks: consider whether denying banking facilities to clients (egby closing an account or refusing to open an account) or denying a bank access to financial networks (egSWIFT) can be justified from a legal perspective - and whether denying access to banking facilities and networks can also serve a (useful?) political purpose or can be an effective way in which to deal with corruption.