In cheque bounce cases under Section 138 of the Negotiable Instruments Act, 1881, a vital requirement is that the cheque must have been issued against a "legally enforceable debt or liability." This means the drawer must owe a sum of money to the payee, either from a loan, goods sold, or services rendered. A cheque issued as a gift or donation does not qualify. Courts examine documentation, invoices, or prior transactions to determine enforceability. The absence of a valid debt can result in dismissal of the complaint.