Res Judicata at the Administrative Appeals Tribunal: Re-opening the Case

It is an unavoidable reality of legal decision-making that individuals may try to re-litigate matters that have already been decided. The question is how decision-makers should deal with these cases. While courts answer this question by applying the doctrine of res judicata, it is yet to be satisfactorily answered in the jurisdiction of the Administrative Appeals Tribunal (AAT). By analysing the respective natures of res judicata and the specific brand of administrative decision-making undertaken by the AAT, this article explores whether res judicata can and should be applied by the AAT. Ultimately, it will conclude that the AAT must apply res judicata where relevant, unless there is an express statutory intention allowing for the decision to be re-made.