Which element of a legal contract requires that each party be of legal age, mentally competent, and not under the influence of drugs or alcohol?

解析

The competent parties element requires that everyone entering the contract have the legal capacity to do so, meaning they are of legal age, of sound mind, and not intoxicated. Legal purpose requires that the contract not be for an illegal aim. Consideration is the value exchanged. Offer and acceptance is the mutual agreement (the meeting of the minds). A contract entered by an incompetent party may be voidable, which is why capacity is a required element.