Previously Section 80 of the Indian Penal Code (IPC)

Nothing is an offence which is done by accident or misfortune, and without any criminal intention or knowledge in the doing of a lawful act in a lawful manner by lawful means and with proper care and caution.

Illustration

A is at work with a hatchet; the head flies off and kills a man who is standing by. Here, if there was no want of proper caution on the part of A, his act is excusable and not an offence.