A natural person who enters a contract possesses complete legal capacity to be held liable for the duties he or she agrees to undertake, unless the person is a minor, mentally incapacitated, or intoxicated. A minor is defined as a person under the age of 18 or 21, depending on the jurisdiction. A contract made by a minor is voidable at the minor’s discretion, meaning that the contract is valid and enforceable until the minor takes some affirmative act to disavow the contract. Minors who choose to disavow their contracts entered may not be held liable for breach. The law assumes that minors are too immature, naïve, or inexperienced to negotiate on equal terms with adults, and thus courts protect them from being held accountable for unwisely entering contracts of any kind.

When a party does not understand the nature and consequences of an agreement that he or she has entered, the law treats that party as lacking mental capacity to form a binding contract. However, a party will not be relieved from any contractual duties until a court has formally adjudicated the issue after taking evidence concerning the party’s mental capacity, unless there is an existing court order declaring the party to be incompetent or insane. Like agreements with minors, agreements with mentally incapacitated persons are voidable at that person’s discretion. However, a guardian or personal representative may ratify an agreement for an incapacitated person and thereby convert the agreement into a legally binding contract.

Contracts entered into by persons under the influence of alcohol and drugs are also voidable at that person’s discretion, but only if the other party knew or had reason to know the degree of impairment. As a practical matter, courts rarely show sympathy for defendants who try to avoid contractual duties on grounds that they were intoxicated. However, if the evidence shows that the sober party was trying to take advantage of the intoxicated party, courts will typically intervene to void the contract. Persons who are intoxicated from prescription medication are treated the same as persons who are mentally incompetent or insane and are generally relieved from their contractual responsibilities more readily than are persons intoxicated from non-prescription drugs or alcohol.