A contract based on an illegal consideration is?

A contract based on an illegal consideration is classified as void. This is due to the fact that contracts must have a legal basis to be enforceable in court. If the consideration, which is the value exchanged in the contract, involves illegal activities or purposes, the contract is inherently unenforceable because it does not align with the principles of law.

For example, if two parties enter into a contract where one party agrees to pay another for committing a crime, that contract is void because the consideration is illegal. Since an agreement's enforceability is contingent upon its legality, any contract that involves illegal consideration cannot be upheld by the legal system, rendering it void from the outset. This ensures that the law does not support or condone illegal actions through contractual agreements.