Cal. Civ. Code § 1643 : CALIFORNIA CIVIL CODE — OBLIGATIONS — CONTRACTS — INTERPRETATION OF CONTRACTS — Lawful, operative, definite, reasonable and capable of being carried into effect TEXT PDF A contract must receive such an interpretation as will make it lawful, operative, definite, reasonable, and capable of being carried into effect, if it can be done without violating the intention of the parties. Ca. Civ. Code § 1643 Enacted 1872.