Lien is a right to retain property belonging to a debtor until the debtor has discharged the debt due to the creditor. This form of protection known as the general lien of bankers arose from usage of trade from time immemorial and is judiciary recognized.
The nature of the securities Subject to the lien must come to the bank in its capacity as a banker and in the course of banking business. Securities held by a bank or deposited with a bank for safe custody are not subject to the lien unless there is an agreement between the parties to the contrary.
Does a lien give the bank the right to sell? a mere lien gives no power of sale, neither does it give a ground for applying to court to grant the power of sale. The method that appears open to a banker for realising securities held under a lien would seem to be to sue for the debt obtain injunction for the debt, and then take the securities in execution of that judgment.
The right of lien extends only to the customers own property and not to property held in trust by the customer for their clients.