CA Civ Code Section 3439.05

(a)

A transfer made or obligation incurred by a debtor is voidable as to a creditor whose claim arose before the transfer was made or the obligation was incurred if the debtor made the transfer or incurred the obligation without receiving a reasonably equivalent value in exchange for the transfer or obligation and the debtor was insolvent at that time or the debtor became insolvent as a result of the transfer or obligation.

(b)

A creditor making a claim for relief under subdivision (a) has the burden of proving the elements of the claim for relief by a preponderance of the evidence.