General exceptions: mistake, accident, necessity and incapacity

1. Excusable and justifiable acts

Writers divide the exceptions into two groups. Excusable acts are those where the doer is not blamed because of some defect in his mind or knowledge: mistake of fact, accident, infancy, insanity, involuntary intoxication. Justifiable acts are those the law approves of in the circumstances: judicial acts, acts done under a court order, necessity, consent, private defence. The distinction helps arrange an essay; it has no other legal effect.

2. Mistake of fact: sections 14 and 17

The maxim is ignorantia facti excusat, ignorantia juris non excusat: ignorance of fact excuses, ignorance of law does not.

• Section 14 (old s.76): nothing is an offence which is done by a person who is, or who by reason of a mistake of fact in good faith believes himself to be, bound by law to do it. Illustrations: a soldier who fires on a mob on his superior's order in conformity with the law; a court officer ordered to arrest Y who, after due enquiry, arrests Z believing him to be Y.
• Section 17 (old s.79): the same protection for a person who is, or by mistake of fact in good faith believes himself to be, justified by law. A seizes Z, whom he sees apparently committing murder, to hand him to the authorities; A commits no offence even if Z was acting in self-defence.

Three conditions follow from the words: the mistake must be of fact, not law; it must be in good faith, which under s.2(11) means with due care and attention; and, if believed true, the facts must make the act lawful. In the English case R v. Tolson (1889), a wife who remarried in the honest and reasonable belief that her husband was dead was acquitted of bigamy. R v. Prince (1875) went the other way because the statute was read as one of strict liability.

The difference between ss.14 and 17 is between bound and justified. A soldier or court officer acts under a legal duty; a private citizen arresting a murderer acts under a legal permission.

3. Judicial acts: sections 15 and 16

A Judge acting judicially in the exercise of a power which is, or which he in good faith believes to be, given to him by law commits no offence (s.15, old s.77). A person who acts in pursuance of a court's judgment or order, while it is in force, is protected even if the court lacked jurisdiction, provided he believed in good faith that it had jurisdiction (s.16, old s.78). The Judges (Protection) Act, 1985 gives parallel civil and criminal protection.

4. Accident: section 18

Nothing is an offence which is done by accident or misfortune, without criminal intention or knowledge, in the doing of a lawful act, in a lawful manner, by lawful means, and with proper care and caution (old s.80). The illustration: A is working with a hatchet, the head flies off and kills a bystander; if A took proper caution, it is no offence. All five conditions must be met. An accident in the course of an unlawful act, or caused by want of care, falls outside s.18; in the second case the act may be negligent homicide under s.106.

5. Necessity: section 19

Nothing is an offence merely because it is done with knowledge that it is likely to cause harm, if it is done without criminal intention to cause harm and in good faith to prevent or avoid other harm to person or property (old s.81). The Explanation makes it a question of fact whether the harm avoided was of such a nature and so imminent as to justify the risk. Illustrations: a captain who alters course to avoid a boat with twenty passengers, risking a boat with two; a man who pulls down houses to stop a fire spreading.

The section does not allow a person to kill one innocent to save himself. In R v. Dudley and Stephens (1884), shipwrecked sailors who killed and ate the cabin boy were convicted of murder: necessity is no defence to the intentional killing of an innocent person.

6. Infancy: sections 20 and 21

• Under seven, s.20 (old s.82): absolute immunity; doli incapax. No evidence of maturity can be led.
• Above seven and under twelve, s.21 (old s.83): qualified immunity. The child is protected only if he has not attained sufficient maturity of understanding to judge the nature and consequences of his conduct on that occasion. Maturity is judged from the conduct itself: concealing the act or running away suggests understanding.

Children above twelve are fully liable under the Sanhita, but are dealt with under the Juvenile Justice (Care and Protection of Children) Act, 2015, not by the ordinary criminal courts.

7. Unsoundness of mind: section 22

Nothing is an offence which is 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 he is doing what is either wrong or contrary to law (old s.84). The BNS uses “unsoundness of mind”, as the IPC did.

The section is based on the M'Naghten rules (1843). M'Naghten, suffering from delusions, shot and killed Drummond, secretary to Sir Robert Peel, whom he mistook for Peel. His acquittal led the House of Lords to put questions to the judges, whose answers state that every man is presumed sane, and that to establish insanity it must be clearly proved that at the time of the act the accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act, or, if he knew it, that he did not know he was doing what was wrong.

Three points to make in every answer:

• Legal, not medical, insanity. Not every mental illness is enough. The cognitive faculty must be so impaired that the accused did not know the nature of the act or that it was wrong or contrary to law.
• The relevant time is the time of the act. Conduct before and after (motive, preparation, concealment, flight) is evidence of the state of mind at that moment.
• Burden. In Dahyabhai Chhaganbhai Thakkar v. State of Gujarat, 1964 INSC 80, AIR 1964 SC 1563, the accused killed his wife and pleaded insanity. The Court held that the prosecution must prove mens rea beyond reasonable doubt; the accused must establish insanity only on a preponderance of probabilities; and even where he fails to prove insanity fully, if the evidence raises a reasonable doubt about one of the ingredients of the offence, including mens rea, he is entitled to acquittal. On the facts, the plea failed.

8. Intoxication: sections 23 and 24

• Section 23 (old s.85): no offence if, by reason of intoxication, the doer was incapable of knowing the nature of the act or that it was wrong or contrary to law, provided the intoxicant was administered without his knowledge or against his will. Voluntary intoxication is no defence.
• Section 24 (old s.86): where an offence requires a particular knowledge or intent, a voluntarily intoxicated person is treated as having the knowledge he would have had if sober.

The section speaks of knowledge, not intention. In Basdev v. State of Pepsu, 1956 INSC 25, AIR 1956 SC 488, a retired military jemadar, drunk at a wedding feast, shot a boy who would not make room for him. The Court held that he was to be taken to know what a sober man would know, but whether he had the intention to kill depended on the evidence of his state of mind; since he was not so drunk as to be unable to form an intention, and the facts showed it, he was liable. The Court approved the House of Lords in Director of Public Prosecutions v. Beard (1920).

How this is examined

As an essay: “Discuss the defence of insanity with reference to the M'Naghten rules”, or “Mistake of fact is a defence but mistake of law is not. Discuss.” As a short note: accident, necessity, child under twelve, intoxication. Problems are common: a person arrests the wrong man in good faith; a child of nine steals and hides the goods; a drunken man stabs a stranger. Name the BNS section, set out its conditions, apply them one by one, and give the old IPC section in brackets.