This slim volume provides an outline study of the doctrine of subrogation. It commences with an examination of the doctrine of the equitable principles governing the doctrine of subrogation and distinguishes it from the assignment of a chose in action. It then explores the circumstances in which subrogation may operate: the right of subrogation to the trustee's right of indemnity; an insurer's right of subrogation; where the right of subrogation vests in a party (other than a surety) who discharges a third party's debt to a secured creditor; a surety who discharges the principal debtor's debt to a secured creditor; and the rights to subrogation of a putative lender who purports to lend money to an ultra vires borrower who then uses the proceeds of the putative loan to discharge its ultra vires debts. It concludes with a consideration of those situations where a third party payer does not have any right to be subrogated to the right of the payee against a debtor. The work contains a useful summary of the essential legal principles by reference to the primary source material and, in doing so, provides a springboard for further detailed research if required. - Anthony Lo Surdo, Australian Banking and Finance Law Bulletin, May-June 2015 Dr Ong's study of the law of subrogation is a useful handbook addressing in turn each of the contexts in which one party may become subrogated to a second party rights against a third party, ie entitled to exercise those rights without assignment. The beneficiaries of the doctrine of subrogation include insureds, trust creditors and sureties, each of whom are considered among others in this study. In addressing this topic in a systematic way, this study delivers a clarity often sought by practitioners to what Dr Ong describes in the preface as an otherwise 'tumultuous' doctrine. - Queensland Law Reporter - 19 December 2014 - [2014] 49 QLR