Jurisprudence, Interpretation and General Laws · Laws relating to Crime and its Procedure

General Exceptions under the Bharatiya Nyaya Sanhita, 2023

Updated 11 October 2026 · Fact-checked

General exceptions under the Bharatiya Nyaya Sanhita, 2023 are situations where an act that looks like an offence is not an offence, such as mistake of fact, unsound mind, infancy or private defence. To solve a question, name the exception, apply its conditions to the facts, then conclude clearly.

Understand General Explanations and Exceptions under BNS

A criminal charge has two sides. The prosecution must show that the act fits the definition of an offence. The accused may then show that the act falls within a general exception. These exceptions apply to offences under the Sanhita unless a provision says otherwise.

The logic is simple. Crime needs a guilty mind in most cases. Where a person could not form a guilty mind, or acted in good faith under the law, or acted to protect a person or property, the law does not punish. Think of the exceptions in three groups: justification and mistake (acts done by a person justified by law, or under a good-faith mistake of fact), incapacity (youth, want of maturity, unsound mind, intoxication) and private defence. Your study material also covers other exceptions, such as accident and necessity. This page focuses on the sections discussed below.

Two sections matter most on the excuse side. Section 17 says nothing is an offence if done by a person who is justified by law, or who, by reason of a mistake of fact and not of law, in good faith believes himself justified by law. So it covers both an act that is actually justified by law and an act done under a good-faith mistake of fact about being justified. Section 22 says nothing is an offence if done by a person who, at the time of doing it, by reason of unsoundness of mind, is incapable of knowing the nature of the act, or that it is wrong or contrary to law. The test is the mental state at the time of the act.

Private defence is the right to protect your body or property, or another person's, against an offence. It has limits. Section 37 says there is no right of private defence against certain acts of public servants acting in good faith (where there is no reasonable apprehension of death or grievous hurt), and none where there is time to seek help from public authorities. It also says the right never extends to inflicting more harm than is necessary for defence.

Section 36 closes a gap. If an act is not an offence only because the doer was a child, immature, of unsound mind, intoxicated or under a misconception, the victim still has the same right of private defence as if it were an offence. So if a person of unsound mind attacks you, you may defend yourself as you would against a sane attacker.

Key rules to remember

Act justified by law or done under mistake of fact (Section 17): Not an offence if done by a person who (a) is justified by law, or (b) by mistake of fact (not of law), in good faith believes himself justified by law in doing it; A mistake of law gives no protection. Good faith is essential. The belief must be that the act is justified by law, not merely that the person is mistaken about some fact.
Act of a person of unsound mind (Section 22): Not an offence if, at the time of the act, unsoundness of mind makes the person incapable of knowing (a) the nature of the act, or (b) that it is wrong or contrary to law; The test is incapacity at the time of the act, not general illness.
Private defence against incapable or mistaken person (Section 36): Act not an offence due to youth, immaturity, unsound mind, intoxication or misconception → victim has the same right of private defence as if it were an offence; The doer is excused, but the victim can still defend.
Limits on private defence (Section 37(1)): No right: (a) against a public servant acting in good faith under colour of office, if no reasonable apprehension of death or grievous hurt; (b) same, if done by direction of such a public servant; (c) where there is time to seek public authorities; Explanations 1 and 2: the right remains unless you know or have reason to believe the person is a public servant or acts on such direction, or authority is stated or produced.
Proportionality (Section 37(2)): Private defence never extends to inflicting more harm than necessary for defence; Excess force loses the protection of the exception.
Procedure for an accused of unsound mind (BNSS Section 368): Court tries the fact of unsoundness and incapacity first, records a finding and postpones proceedings → refers the accused to a psychiatrist or clinical psychologist → if informed the accused is of unsound mind, decides whether the accused is incapable of entering defence → if incapable, examines the prosecution record and hears the advocate: no prima facie case → discharge and deal with the accused under Section 369; prima facie case → postpone the trial for the treatment period, but if the incapacity is by reason of intellectual disability, no trial is held and the accused is dealt with under Section 369 (Section 368(4)); Section 367 gives the parallel procedure for a Magistrate holding an inquiry.
Charge and exceptions (BNSS Section 234(5)): Making a charge = stating that every legal condition required to constitute the offence was fulfilled; Illustration (a) shows a murder charge implies the act did not fall within any general exception.

How to solve General Explanations and Exceptions under BNS questions

Use the same five-part answer for any problem question. ICSI-style answers reward the provision, the analysis and a firm conclusion.

1Read the facts and list the act done, the state of mind of the doer and the circumstances.
2Identify the exception raised: mistake of fact, unsound mind, infancy, intoxication, accident or private defence.
3State the rule in plain words and cite the section if you are sure of it, for example Section 17, 22, 36 or 37 of the BNS.
4Apply each condition to the facts one by one, such as good faith, time of the act, knowledge of the nature of the act, or proportion of force.
5Check for limits: mistake of law, time to approach authorities, excess force, or a voluntary state.
6Consider the victim's side: does Section 36 give the other person a right of private defence?
7Write a clear conclusion: offence or no offence, and why.
8If the accused is of unsound mind and facing trial, add the BNSS procedure (Section 368 for courts, Section 367 for a Magistrate's inquiry). Once the accused is found incapable of entering defence, the court checks for a prima facie case. If there is none, it discharges the accused and deals with him under Section 369. If there is one, it postpones the trial for treatment. But where the incapacity is by reason of intellectual disability, it does not hold the trial and deals with the accused under Section 369 (Section 368(4)).

Quickest way: Four-question check

When to use it: Use this when you have little time and need a structured answer fast.

Ask: was the doer able to understand or intend the act? (unsound mind, infancy, intoxication)
Ask: did the doer honestly believe a fact that would make the act lawful? (mistake of fact, Section 17)
Ask: was the act a response to a threat, and was the force within what was necessary? (private defence, Section 37)
Ask: is there a limit that removes the protection? (mistake of law, time to seek authorities, excess harm)
Write: rule, application, conclusion in three short paragraphs.

Common mistakes in General Explanations and Exceptions under BNS

Treating any mistake as a defence.
Students remember that mistake is an exception but forget the condition.
Fix: Write that only a mistake of fact in good faith protects under Section 17. A mistake of law does not.
Applying the unsound mind exception because the accused has a mental illness.
Students confuse medical illness with legal incapacity.
Fix: State the Section 22 test: at the time of the act, was the person incapable of knowing the nature of the act or that it was wrong or contrary to law?
Saying there is no right of private defence against a person of unsound mind or a mistaken person.
Students think no offence means no defence is needed.
Fix: Cite Section 36. The victim has the same right of private defence as against a sane, non-mistaken attacker.
Ignoring the limit on force.
Students focus on the right and skip Section 37(2).
Fix: Always check whether the harm caused was more than necessary. If it was, the protection fails.
Claiming private defence against any public servant.
Students remember only the headline that the right exists.
Fix: Apply Section 37(1)(a) and (b): no right against a public servant acting in good faith under colour of office if there is no reasonable apprehension of death or grievous hurt. Check the Explanations too.
Mixing up criminal procedure for unsound mind with the substantive exception.
Both topics use the words unsound mind.
Fix: Keep two layers: Section 22 BNS decides whether the act is an offence. Sections 367 and 368 BNSS decide whether the accused can be tried.

Worked examples

Example 1

Ravi sees a man enter his neighbour's house at night and, believing him to be a thief, attacks him. The man was the neighbour's son, entitled to enter. Discuss the liability of Ravi and the rights of the son.

Show the solution

Rule: Section 17 says nothing is an offence done by a person who is justified by law, or who, by mistake of fact and not of law, in good faith believes himself justified by law in doing it.
Application to Ravi: Ravi was mistaken about a fact, namely who the man was. His protection under Section 17 depends on whether, because of that mistake, he honestly believed that the law justified what he did. Merely attacking a suspected thief does not by itself make him justified by law, so this must be shown on the facts. Good faith is essential, and a mistake about the law gives no protection.
Limits: Private defence never extends to more harm than necessary (Section 37(2)). Where there is time to have recourse to the protection of public authorities, there is no right of private defence (Section 37(1)(c)). Whether Ravi had time to call for help, and whether his force was proportionate, are questions of fact.
The son's position: Section 36 Illustration (b) deals with a similar case. A person enters a house he is legally entitled to enter, and another, in good faith taking him for a house-breaker, attacks him. The illustration says the attacker, acting under this misconception, commits no offence. But the person attacked has the same right of private defence against the attacker as he would have if the attacker were not acting under that misconception. The son therefore has a right of private defence against Ravi, within the limit of necessary force.

Answer: Ravi may escape liability only if he acted in good faith and his mistake of fact led him to believe he was justified by law, and his force stayed within the limits of Section 37. This depends on the facts and cannot be assumed. The son, by Section 36 Illustration (b), has the same right of private defence against Ravi as if Ravi were not mistaken, limited to necessary force.

Example 2

Meena, a person of unsound mind, attacks Arjun with a knife and tries to kill him. Arjun hits her with a stick to stop her. Later Meena is brought for trial. Explain Arjun's position and what the Court must do about Meena.

Show the solution

Rule on Meena's act: Section 22 BNS says nothing is an offence done by a person who, at the time, by reason of unsoundness of mind, is incapable of knowing the nature of the act or that it is wrong or contrary to law. If Meena meets this test, she is not guilty of an offence.
Rule on Arjun: Section 36 says that where an act is not an offence because of unsoundness of mind, every person has the same right of private defence as if the act were an offence. Arjun may therefore defend himself as against a sane attacker.
Limit: Under Section 37(2), Arjun may not inflict more harm than necessary. Using a stick to stop a knife attack is a matter of fact to be judged on proportion.
Procedure, first stage: If it appears at trial that Meena is of unsound mind and consequently incapable of making her defence, the Court under BNSS Section 368(1) must first try that fact, consider medical and other evidence, record a finding and postpone further proceedings. Under Section 368(2) it refers her to a psychiatrist or clinical psychologist for care and treatment, who reports whether she is suffering from unsoundness of mind.
Procedure, second stage: If the Court is informed that she is of unsound mind, Section 368(3) requires it to decide whether the unsoundness renders her incapable of entering defence. If she is, it records a finding, examines the prosecution record and hears her advocate without questioning her. If there is no prima facie case, it discharges her and deals with her under Section 369. If there is a prima facie case, it postpones the trial for the period the psychiatrist or clinical psychologist considers necessary for treatment.
Special case: Under Section 368(4), if there is a prima facie case and she is incapable of entering defence by reason of intellectual disability, the Court does not hold the trial and orders her to be dealt with under Section 369.

Answer: Arjun has the right of private defence under Section 36, limited by Section 37(2). Meena is not guilty if she meets the Section 22 test, and the Court must follow the procedure in BNSS Section 368 before any trial continues. That procedure ends in discharge, postponement for treatment, or, for intellectual disability with a prima facie case, no trial and action under Section 369.

Exam tips

Write the section number only for provisions you are sure of. Sections 17, 22, 36 and 37 of the BNS are safe to cite from this guide.
In problem questions, always finish with a one-line conclusion. ICSI answers lose marks when the analysis has no clear end.
Compare similar pairs when asked: mistake of fact versus mistake of law, and a person excused by an exception versus a person against whom defence is allowed.
Use short headings in your answer script: Provision, Facts and analysis, Conclusion.
Mention the BNSS procedure when the accused is of unsound mind, since examiners like answers that link substantive and procedural law.

Practice questions from Laws relating to Crime and its Procedure

General Explanations and Exceptions under BNS: frequently asked questions

What is the difference between mistake of fact and mistake of law under BNS?

Under Section 17, only a mistake of fact made in good faith protects the doer. A mistake of law, such as not knowing that an act is illegal, does not make the act lawful.

Does unsound mind always protect an accused under BNS?

No. Section 22 applies only if, at the time of the act, unsoundness of mind made the person incapable of knowing the nature of the act or that it was wrong or contrary to law. General illness alone is not enough.

Can you use private defence against a person who is not guilty of an offence?

Yes. Section 36 gives the same right of private defence where the act is not an offence due to youth, immaturity, unsound mind, intoxication or misconception. The right is still limited by Section 37.

Is there private defence against a police officer?

Section 37(1) removes the right against a public servant acting in good faith under colour of office if there is no reasonable apprehension of death or grievous hurt. The Explanations say you keep the right unless you know or have reason to believe the person is a public servant, or the conditions for authority are met.

What happens when an accused is of unsound mind at trial?

Under BNSS Section 368, the Court first decides the question of unsoundness and incapacity and refers the accused to a psychiatrist or clinical psychologist. If the accused is incapable of entering defence, the Court discharges him if there is no prima facie case, dealing with him under Section 369, or postpones the trial for treatment if there is one. Where the incapacity is by reason of intellectual disability and a prima facie case exists, no trial is held and the accused is dealt with under Section 369.