Section 138 of the Negotiable Instruments Act, 1881, is the primary provision that makes the dishonour of a cheque for insufficiency of funds a criminal offence. It creates a statutory offence, making a person who issues a cheque that bounces liable for imprisonment for a term which may extend to two years, or with a fine which may extend to twice the amount of the cheque, or with both. The subsequent sections (139-142) lay down the presumptions, defences, and procedures related to the prosecution of an offence under Section 138.