Cal. Code of Civil Procedure § 871.1 : Actions In Particular Cases — California Code Of Civil Procedure — Good Faith Improver Of Property Owned By Another — Good faith improver defined Date: 1 Aug 2016 TEXT PDF Current through the 2016 Legislative Session as used in this chapter, "good faith improver" means: (a) A person who makes an improvement to land in good faith and under the erroneous belief, because of a mistake of law or fact, that he is the owner of the land. (b) A successor in interest of a person described in subdivision (a). Ca. Civ. Proc. Code § 871.1