Challenge Bank Ltd v Mailman

Challenge Bank Ltd (the appellant) appealed to the New South Wales Court of Appeal against a decision of the Supreme Court of New South Wales. The dispute concerned the enforceability of a guarantee provided by Mr Mailman (the respondent) in favour of the appellant. The appellant sought to recover moneys owed under the guarantee, which had been provided in relation to a loan facility extended to a company.

The primary legal issue before the Court of Appeal was whether the respondent was discharged from his obligations under the guarantee due to the appellant's conduct. Specifically, the court had to determine if the appellant had, by its actions or omissions, fundamentally altered the nature of the principal debtor's obligations or increased the respondent's risk as guarantor, thereby releasing him from liability.

The Court of Appeal found that the appellant had, without the respondent's consent, varied the terms of the principal debtor's loan facility. This variation involved an increase in the principal amount and an extension of the repayment period. The court held that such a material alteration to the underlying debt, which prejudiced the guarantor, operated to discharge the respondent from his obligations under the guarantee. The legal principle applied was that a creditor's conduct that materially alters the principal debtor's obligations without the guarantor's consent will release the guarantor from liability.

The appeal was dismissed, and the decision of the Supreme Court in favour of the respondent was affirmed.