General law
Among other obligations, banks are subject to a general duty of confidentiality which was confirmed by an English decision known as Tournier's Case.
This general duty is owed to all customers - whether individuals, corporations or trusts, for example - and no matter why they've obtained the banking service.
But there are four exceptions - the bank may disclose information if:
- required by law;
- compelled by duty to the public;
- the customer consents;
- the bank's interests require disclosure - there's limited case law, but it's likely this exception only applies if the bank is preserving or protecting its interests in relation to the customer. For example, a bank may disclose the state of its customer's indebtedness in legal proceedings to recover a debt.
There is also authority that disclosure by a wholly owned subsidiary to its parent may breach a banker's duty of confidence.
