Cal. Civ. Code § 1550 : CALIFORNIA CIVIL CODE — OBLIGATIONS — CONTRACTS — NATURE OF A CONTRACT — DEFINITION — Essential to existence of contract TEXT PDF It is essential to the existence of a contract that there should be: 1. Parties capable of contracting; 2. Their consent; 3. A lawful object; and, 4. A sufficient cause or consideration. Ca. Civ. Code § 1550 Enacted 1872.