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Section 12 of the Indian Contract Act, 1872 deals with the capacity of a person to contract with regard to his state of mind. A person is said to be of sound mind for the purpose of making a contract if, at the time of making the contract, he is capable of understanding it and of forming a rational judgment as to its effect upon his interests.

Thus, the important point is not whether a person is generally of sound or unsound mind, but whether he is capable of understanding the particular contract at the time when the contract is made.

A person who is usually of unsound mind but occasionally of sound mind may enter into a valid contract during the period when he is of sound mind. On the other hand, a person who is usually of sound mind but occasionally becomes of unsound mind cannot enter into a valid contract during such period of unsoundness.

  • For example, a patient in a lunatic asylum who is occasionally of sound mind may enter into a contract during those intervals. Similarly, a person who is normally sane but is delirious because of fever, or is so intoxicated that he cannot understand the terms of the contract or form a rational judgment about its effect on his interests, cannot contract during that period.

The test under Section 12 is therefore capacity to understand the transaction and form a rational judgment regarding its effect on one’s interests.

Burden of Proof under Section 12

The law presumes every person to be of sound mind unless proven otherwise. The burden of proving unsoundness of mind at the time of contract rests on the party who asserts it.

If a person is shown to be usually of unsound mind (e.g., adjudged insane by a court), the burden shifts to the party asserting that the contract was executed during a lucid interval.

Recognised Categories of Unsoundness of Mind

  1. Idiots: Persons who have completely lost their mental faculties from birth (congenital deficiency). Their agreements are permanently void ab initio (Inder Singh v. Parmeshwardhari Singh).
  2. Lunatics or Insane Persons: Persons whose mental capacity is affected by disease, trauma, or mental illness, but who may experience periods of sanity (lucid intervals). Contracts made during lucid intervals are valid and binding.
  3. Drunken or Intoxicated Persons: Persons temporarily deprived of the power of understanding or forming a rational judgment due to severe intoxication or delirium. Contracts made during such state are void.

Mere Weakness of Mind is Not Unsoundness of Mind

Mere weakness of intellect, simplicity of mind or inability to manage one’s affairs according to ordinary standards does not by itself make a person of unsound mind. The court has to determine whether the person was actually incapable of understanding the transaction and forming a rational judgment at the relevant time.

  • In Inder Singh v. Parmeshwardhari Singh (1957), a person agreed to sell property worth about ₹25,000 for only ₹7,000. It was proved that he was a born idiot and was incapable of understanding the transaction. The court held the sale to be void. The court emphasised that the crucial question was whether the person understood what he was doing and was capable of forming a rational judgment regarding his interests.
  • In R. Lingaraj v. Parvathi (1975), the court distinguished between mere weakness of intellect and unsoundness of mind. A person is not to be treated as of unsound mind merely because his ability to manage his affairs is below the ordinary standard. There must be such mental incapacity as makes him unable to understand the transaction and form a rational judgment concerning it.
  • In Rajinder Kaur v. Mangal Singh (1987), it was held that mere simplicity of mind or weak intellect does not mean that a person is an idiot or of unsound mind. The ultimate question of whether a person was of unsound mind is to be determined by the court, although expert evidence may be taken into consideration.

Position of a Person of Unsound Mind

A person who is incapable of understanding the contract and forming a rational judgment regarding its effect on his interests cannot enter into a valid contract during that period. His agreement is therefore void against him.

However, such a person is not incapable of receiving benefits under a transaction. Further, under Section 68 of the Indian Contract Act, the property of a person incapable of contracting is liable for payment for necessaries supplied to him or to any person whom he is legally bound to support. The liability is against his property and not a personal contractual liability.

The same principle applies to a person who is temporarily incapable of contracting because of delirium, extreme intoxication or a similar condition. What matters is his mental capacity at the time of entering into the particular transaction.

Regarding the restoration of benefits received under a void agreement, Section 65 of the Indian Contract Act applies where an agreement is discovered to be void; however, much like in the case of minors, courts generally hold that Section 65 does not extend to transactions that are void ab initio due to contractual incompetence under Section 11. Instead, the matter is governed by Section 33 of the Specific Relief Act, 1963. Under this provision, where a transaction is cancelled or successfully defended on the ground of unsoundness of mind, the court may, on equitable principles, require the restoration of any benefit or money received by the person of unsound mind, strictly to the extent that his estate has benefited therefrom.

Thus, Section 12 does not require a person to be permanently sound in mind. It requires him to possess sufficient mental capacity at the particular time of making the contract.