Article 1. General of California Evidence Code >> Division 5. >> Chapter 3. >> Article 1.

(a) A presumption is an assumption of fact that the law requires to be made from another fact or group of facts found or otherwise established in the action. A presumption is not evidence.
  (b) An inference is a deduction of fact that may logically and reasonably be drawn from another fact or group of facts found or otherwise established in the action.

A presumption is either conclusive or rebuttable. Every rebuttable presumption is either (a) a presumption affecting the burden of producing evidence or (b) a presumption affecting the burden of proof.

A statute providing that a fact or group of facts is prima facie evidence of another fact establishes a rebuttable presumption.

A presumption affecting the burden of producing evidence is a presumption established to implement no public policy other than to facilitate the determination of the particular action in which the presumption is applied.

The effect of a presumption affecting the burden of producing evidence is to require the trier of fact to assume the existence of the presumed fact unless and until evidence is introduced which would support a finding of its nonexistence, in which case the trier of fact shall determine the existence or nonexistence of the presumed fact from the evidence and without regard to the presumption. Nothing in this section shall be construed to prevent the drawing of any inference that may be appropriate.

A presumption affecting the burden of proof is a presumption established to implement some public policy other than to facilitate the determination of the particular action in which the presumption is applied, such as the policy in favor of establishment of a parent and child relationship, the validity of marriage, the stability of titles to property, or the security of those who entrust themselves or their property to the administration of others.

The effect of a presumption affecting the burden of proof is to impose upon the party against whom it operates the burden of proof as to the nonexistence of the presumed fact.

When a presumption affecting the burden of proof operates in a criminal action to establish presumptively any fact that is essential to the defendant's guilt, the presumption operates only if the facts that give rise to the presumption have been found or otherwise established beyond a reasonable doubt and, in such case, the defendant need only raise a reasonable doubt as to the existence of the presumed fact.