In contract law, what doctrine states that a contract must involve a legal act?

The doctrine that a contract must involve a legal act is rooted in the concept of legality. This principle asserts that for a contract to be valid and enforceable, it must pertain to actions or agreements that are permissible under the law. If the subject matter of the contract is illegal or against public policy, then the contract cannot be upheld in a court of law.

This ensures that all parties are engaging in lawful activities and responsibilities in their contractual relationships. For example, a contract for the sale of illegal substances or a contract that requires someone to perform an illegal act would be considered void due to lack of legality. This foundational concept protects both the parties involved and the integrity of the legal system by disallowing agreements that could cause harm or violate legal standards.