People sometimes assume that a contract signed after drinking alcohol or using drugs is automatically unenforceable. Contract law is generally more demanding. Intoxication can affect capacity, but the existence of alcohol or drug use alone does not establish that a person lacked the legal ability to assent.
The Functional Inquiry
The central question is whether the person was so impaired that he or she could not understand the nature and consequences of the transaction or could not act reasonably in relation to it. Mild impairment, poor judgment, or later regret is not necessarily enough.
The Other Party’s Knowledge Matters
Capacity doctrine commonly considers whether the other contracting party knew or had reason to know of the impairment. That requirement helps distinguish an ordinary agreement involving someone who had consumed alcohol from a transaction in which one party knowingly takes advantage of a person who is visibly incapable of understanding what is happening.
Voidable Rather Than Automatically Void
When intoxication satisfies the legal standard, the agreement is commonly treated as voidable rather than nonexistent from the beginning. The impaired party may have the ability to disaffirm, subject to rules concerning restoration of benefits, ratification after sobriety, and protection of innocent third parties.
Evidence of Capacity
Relevant facts may include coherence of speech, ability to negotiate terms, understanding of price and subject matter, memory of the transaction, complexity of the agreement, witnesses, communications before and after signing, and the conduct of the other party.
Voluntary Intoxication Does Not Eliminate the Doctrine
Although voluntary intoxication may affect how a court views the equities, capacity doctrine is still concerned with genuine assent. The law seeks to protect transactions from opportunistic avoidance while also preventing enforcement when a party knowingly obtained apparent assent from someone who lacked meaningful understanding.
The practical lesson is simple: intoxication is a fact, not the legal conclusion. Enforceability depends on the severity of impairment, the person’s functional capacity at the moment of agreement, and the other party’s knowledge of the condition.