In Isaacson v. California Ins. Guarantee Assn.(1988) 44 Cal.3d 775, the Supreme Court acknowledged the rule that where an insurer breaches a contractual duty to defend and the insured settles the underlying lawsuit on its own behalf, a rebuttable evidentiary presumption arises: "In a later action against the insurer for reimbursement based on a breach of its contractual duty to defend the action, a reasonable settlement made by the insured to terminate the underlying claim against him may be used as presumptive evidence of the insured's liability on the underlying claim, and the amount of such liability. " (Id. at pp. 791-792.) According to the court, the presumption operates "where the insurer has wrongfully refused to cover or defend a claim, leaving the insured to mount his own defense or suffer a default. In order to recover reimbursement from the insurer, the insured must demonstrate that the claim was covered under the policy in question, or that the insurer breached its duty to defend. Once a breach of contract is proved, the insured's act of settling the claim is said to raise the presumption that the third party's claim against him was legitimate, and that he was liable in the amount which he agreed to pay in settlement. " (Id. at pp. 793-794.)