SZEEO v MIMIA

The High Court of Australia considered an appeal by SZEEO against a decision of the Full Federal Court concerning the interpretation of a settlement agreement. The dispute arose from an earlier proceeding where SZEEO had sought to recover damages for personal injury sustained in a motor vehicle accident. Following that proceeding, SZEEO and the respondent, MIMIA (the Motor Accidents Insurance Board of Tasmania), entered into a settlement agreement. SZEEO later sought to reopen the settlement, alleging that the agreement was void due to a fundamental mistake regarding the extent of his injuries.

The central legal issue before the High Court was whether the settlement agreement was void at common law due to a common mistake as to the existence of a vital fact, namely the true extent of SZEEO's injuries. This required the Court to consider the principles governing the avoidance of contracts due to common mistake, particularly in the context of personal injury settlements. The Court had to determine if the mistake was so fundamental as to render the agreement void *ab initio*, or if the agreement, properly construed, allocated the risk of such a mistake between the parties.

The High Court held that the settlement agreement was not void for common mistake. Their Honours reasoned that the parties, by entering into the settlement, had intended to resolve all claims arising from the accident, including any uncertainty about the future progression or extent of SZEEO's injuries. The agreement was not predicated on the assumption that SZEEO's condition would remain static, but rather on the mutual intention to achieve finality. The Court applied the principle that a contract will not be void for common mistake unless the mistake is so fundamental that the subject matter of the contract is essentially different from what the parties believed it to be, and that the contract does not, on its proper construction, allocate the risk of such a mistake. In this instance, the settlement agreement was construed as having allocated the risk of unforeseen developments in SZEEO's condition to SZEEO himself.

The appeal was dismissed.