Indian Penal Code, 1860
Section 43
repealedIllegal . Legally bound to do
The word “illegal” is applicable to everything which is an offence or which is prohibited by law, or which furnishes ground for a civil action; and a person is said to be “legally bound to do” whatever it is illegal in him to omit.
Why this exists
This is a definitions clause from the IPC's introductory chapter. The drafters (led by Macaulay) wanted precise, reusable meanings for common words used throughout the Code, so that terms like 'illegal' and 'legally bound to do' wouldn't need to be redefined in every section. This avoids ambiguity when the Code says someone acted 'illegally' or failed to do something they were 'legally bound' to do.
How courts read it
Courts have used this definition to interpret offences built around omissions—for example, deciding whether a public servant's failure to act was 'illegal' because it was prohibited by service rules or because it exposed the government to a civil claim, not only when it was itself a separate crime. The three-part definition (offence / prohibited by law / civil-action ground) is treated as exhaustive, so something not fitting any limb is not 'illegal' for IPC purposes.
Common misconceptions
- Myth: 'Illegal' under the IPC only means acts that are criminal offences.
Fact: Section 43 says 'illegal' also includes acts prohibited by any law (even non-criminal) and acts or omissions that give grounds for a civil lawsuit. - Myth: 'Legally bound to do' means a moral or social duty.
Fact: It specifically means an omission that would itself be 'illegal' under the three-part definition—criminal, prohibited, or civilly actionable—not just any expected behavior.