Yes, and this is a crucial protective remedy under Indian law, since a sale deed executed by a person who was of unsound mind at the time of execution lacks the fundamental element of free and genuine consent that every valid contract requires, making such a transaction voidable and, in many cases, entirely void depending on the severity and nature of the mental incapacity involved. Under Section 12 of the Indian Contract Act, 1872, a person is considered to have sound mind for the purpose of making a contract if they are capable of understanding the contract and forming a rational judgment about its effect on their interests, and where this capacity was genuinely absent at the time of executing a sale deed, the transaction can be successfully challenged and cancelled.

Establishing that a person was of unsound mind at the specific time of execution requires careful and often medically substantiated evidence, since courts distinguish between someone experiencing periodic episodes of unsoundness who may have executed the document during a lucid interval, versus someone with a more permanent or progressive condition affecting their capacity throughout. Medical records contemporaneous with the execution date, testimony from treating physicians, and evidence from family members or others who interacted with the person around that specific time all become important in establishing the person's actual mental state when the sale deed was signed.

Where the sale deed was executed on behalf of a person already under a formal guardianship order due to established mental incapacity, without proper court sanction for the specific transaction, this provides particularly strong grounds for cancellation, since the guardian's authority to deal with the ward's property is itself constrained by the terms of the guardianship and generally requires specific court permission for significant transactions like property sale. Even without prior formal guardianship, if it can be established through medical and circumstantial evidence that the person genuinely lacked capacity to understand the nature and consequences of the sale at the time of signing, the transaction remains vulnerable to challenge.

To seek cancellation, the affected person, or where they remain incapacitated, their legally appointed guardian or concerned family members acting on their behalf, can file a suit under Section 31 of the Specific Relief Act, 1963 seeking a declaration that the sale deed is void due to the seller's lack of capacity, along with cancellation of the document and recovery of possession where the property has already been transferred to a buyer. Where the buyer had knowledge of the seller's mental incapacity and proceeded regardless, this adds an element of complicity that strengthens the case for cancellation considerably.

Given how these cases require careful medical and legal evidence establishing incapacity at the precise time of execution, thorough preparation with appropriate expert support is essential to success. The team at Aapka Legal Advice helps families gather the necessary medical and legal evidence to challenge sale deeds executed by persons of unsound mind. The Top Property Lawyers in Mumbai team has successfully secured cancellation of such sale deeds before Mumbai's civil courts, supported by a panel of retired judges experienced in capacity and guardianship matters and criminal lawyers where the buyer's complicity suggests fraud. If a family member's property in Mumbai was sold while they lacked the mental capacity to genuinely consent, gathering strong medical evidence of their condition at the time of execution is the essential foundation for a successful cancellation suit.