II. Chapter Objectives Define contract. List the elements necessary to form a valid contract. Distinguish between bilateral and unilateral contracts. Describe and distinguish between express and implied-in-fact contracts. Describe and distinguish among valid, void, voidable, and unenforceable contracts. III. Key Question Checklist What body of contract law will control the formation, rights, duties, and remedies of this agreement? Are the four elements of a contract in place? How is this contract defined? Formal or informal? Executed or executory? . Are there any defenses that make the contract unenforceable