An attempted contract that is made for an illegal purpose or that is against public policy cannot be enforced by either party and is void. In contrast, a contract that is made by a minor (usually under age 18), or that is based on a mutual mistake, or that was made on the basis of a fraudulent misrepresentation by one party, is voidable and may be rejected by a party who was at a disadvantage when the contract was made. A voidable contract may also be ratified and accepted by such a party—after a child reaches the age of majority (usually 18), or the parties become aware of their mutual mistake, or a party learns of the other party’s misrepresentation and proceeds with performance of the contract.

In Michigan, contracts made for illegal purposes or against public policy are void and unenforceable. This aligns with general contract law principles that prohibit the enforcement of agreements that involve illegal acts or that significantly contravene societal standards. On the other hand, contracts involving minors, mutual mistakes, or fraudulent misrepresentations are categorized as voidable. This means that the disadvantaged party, such as a minor, a party to a mutual mistake, or a victim of fraud, has the discretion to either reject or ratify the contract. For minors, this option to affirm or disaffirm the contract typically becomes available upon reaching the age of majority, which is 18 in Michigan. If a party discovers a mutual mistake or fraudulent misrepresentation but chooses to continue with the contract, this may constitute ratification, making the contract binding. It's important to note that specific statutes and case law can modify these general principles, and an attorney can provide detailed guidance based on the particular circumstances of a contract dispute.