What is Mental Capacity to Contract?

To enter into a contract, a person must have mental capacity sufficient to understand the nature and consequences of her actions. If mental capacity is absent, the contract is voidable by the person lacking capacity. There are three classes of persons commonly understood to lack capacity to be bound by contractual promises:

Do Minors have Mental Capacity to Contract?

A minor is someone below the statutory age of mental capacity within a jurisdiction. Generally, a person must be 18 years old or older to have the requisite mental capacity to contract. As such, a minor who enters into a contract can void the contract at any time prior to reaching the age of majority. The exception to this rule is when the contract involves goods or services necessary for the childs survival. This could include food, water, shelter, etc. In the case of necessities, the child will be obligated to pay the reasonable value of the goods or services received. If the child fails to disaffirm the contract by this time, she thereby ratifies the contract and is bound going forward.

• Example: Jane is 17 years old. She goes to a local gym and signs up for a year-long membership. This is not a contract for a necessity. Jane will be able to void the contract at any time before she turns 18 years old. She will, however, have to pay the reasonable cost of any value she receives from the gym.

Does an Intoxicated Person have Mental Capacity to Contract?

An intoxicated person may lack the mental capacity necessary to contract. Generally, this will require extreme intoxication. If the intoxicated person enters into a contract, she must disaffirm the contract within a reasonable time of regaining capacity and learning of the contract. If she fails to do so within a reasonable time, she has ratified the contract and will be bound.

• Example: Don gets incredibly drunk in a bar. He does not know where he is and asks a stranger for a ride home. He offers to give the stranger, Gary, his Rolex watch in exchange for a ride home. Gary takes him home and takes the Rolex. When Don sobers up, he can immediately demand return of the Rolex. He was too intoxicated to appreciate the nature of his actions. As such, he can void the contract. He must act within a reasonable period to void the contract upon becoming sober.

Does a Mentally Incompetent Person have Mental Capacity to Contract?

A mentally incompetent person generally lacks the ability to enter into a contract. If the mental incompetency is temporary, the individual must disaffirm any contract entered into during incapacity within a reasonable time of regaining capacity. If the person is permanently incapacitated, the contract is either void or voidable at the insistence of a legally appointed guardian.

• Example: Ernie is having psychotic delusions. He goes to a security firm and hires a private security guard. Ernie's legally appointed caretaker will be able to void the contract based upon Ernie's lack of mental competence to enter into the agreement.

Each state may pass additional situations in which it deems an individual mentally incompetent to enter into contractual relations.

Next Article: Lawful Purpose for Contracts Back to: CONTRACT LAW

Related Topics

• What is a Contract?
• Sources of contract law?
•  Unilateral Contract vs a Bilateral Contract?
• Express Contract vs an Implied Contract?
• Offer, Acceptance, Consideration?
• Enforceable Contract vs. a Valid Contract?
• What is a Void Contract vs a Voidable Contract?
• Adhesion Contract 
• Requirement of a Lawful Purpose?
• Common types of Voidable Contract?