Indian criminal law | Definitions
IPC Section 43: Meaning of Illegal and Legally Bound to Do
Section 43 of the Indian Penal Code, 1860 defined the expressions "illegal" and "legally bound to do". The corresponding provision in the Bharatiya Nyaya Sanhita, 2023 is Section 2(15).
Text and meaning of IPC Section 43
Section 43 explained that the term "illegal" covers three kinds of conduct: conduct amounting to an offence, conduct prohibited by law, and conduct furnishing grounds for a civil action. It further explained that a person is "legally bound to do" something when omission of that act would be illegal.
Corresponding provision: BNS Section 2(15)
Section 2(15) of the Bharatiya Nyaya Sanhita, 2023 preserves the same substantive definition of both expressions. The BNS consolidates these general definitions in Section 2 rather than retaining the IPC's original numbering. This definition helps interpret provisions that use these expressions; it does not independently create an offence or prescribe a penalty.
| Provision | Subject | Position |
|---|---|---|
| IPC Section 43 | Illegal; legally bound to do | Historical IPC definition, relevant subject to repeal and savings |
| BNS Section 2(15) | Illegal; legally bound to do | Corresponding definition under the BNS |
| BNS Section 358 | Repeal and savings | Addresses the repeal of the IPC and preservation of specified prior legal effects |
What counts as illegal?
An offence: An act or omission that satisfies the ingredients of a punishable offence under the applicable law. A prohibition by law: Conduct that a valid legal rule forbids, even if the particular prohibition does not by itself establish the criminal offence alleged. A ground for civil action: Conduct that gives an affected person a legally recognised basis to bring a civil claim, depending on the circumstances.
The expression is therefore broader than conduct that is criminally punishable. Whether a particular act is illegal must still be established under the relevant substantive law.
What does legally bound to do mean?
A person is legally bound to perform an act when failure to perform it would itself be illegal. The duty must arise from an applicable legal obligation; a moral expectation or a voluntary courtesy does not, by itself, establish the statutory requirement.
Illustrative examples
Example 1: If a statute requires a specified person to file a legally mandated return and omission is prohibited, that person may be legally bound to file it. The consequences depend on the statute and its exceptions.
Example 2: A contractual or other civil obligation may provide grounds for civil action when breached. That does not automatically mean that the breach is a criminal offence.
Example 3: Where a criminal provision requires proof that someone was legally bound to act, the court must identify the legal duty and determine whether the required elements of that offence are satisfied.
IPC repeal and the application of older law
The BNS repealed the IPC through Section 358, with savings provisions. Whether an earlier IPC provision applies to an incident, investigation or proceeding depends on the relevant dates, the applicable savings provisions and other governing law. A change in statutory numbering should not be treated as retrospectively changing liability without examining those rules.
Official legal references
- India Code: Bharatiya Nyaya Sanhita, 2023 (official PDF) - Sections 2(15) and 358.
- India Code: BNS Act record - statutory details and enforcement date.
- National Crime Records Bureau: BNS chapter and section reference.
Frequently asked questions
What does illegal mean under IPC Section 43?
It includes anything that is an offence, is prohibited by law, or furnishes ground for a civil action.
What does legally bound to do mean?
A person is legally bound to do something when omission of that act would be illegal.
What is the corresponding provision in the BNS?
Section 2(15) of the Bharatiya Nyaya Sanhita, 2023 retains the definition.
Does Section 43 itself prescribe punishment?
No. It is an interpretive definition; liability and punishment depend on the substantive law and facts.
Updated: 28 October 2026. This article provides general legal information, not advice on a particular case.