IRRATIONALITY Decisions should be and also appear to be rational and reasonable. An absence of rationality can result in finding that the decision is infected with jurisdictional error. An example of this is when a decision maker acts on material that forms an “inadequate” basis for the findings made. This is because the inadequacy may support an inference that the decision-maker had applied the wrong test or was not “in reality satisfied of the requisite matters”63. The demonstration of a defect in an irrational or unreasonable decision may lie in the evidentiary foundation relied on or available, or the logical process by which conclusions are sought to be drawn from it64. Moreover, decision-makers cannot merely engage in speculation, or rely on suspicions or impressions in forming reasons for decisions65.
When decisions involve serious findings such as, perjury, dishonesty, forgery or fraud, decision makers are under a stronger obligation carefully to examine all the facts and base conclusions on proper foundations66. Failure to do so can result in a court holding that the decision maker demonstrated such a “closed state of mind” that a finding of ostensible bias could be made67. In Applicant M164/2002 v Minister for Immigration and Multicultural and Indigenous Affairs 68 Lee J stated:
“Serious findings of forgery, fraud or perjury cannot be based on a superficial examination of relevant events and materials, particularly where the conclusion reflects no more than a suspicion held by the Tribunal, and where the suspicion remains untested by reasonable use of powers available to the Tribunal to have further enquiries made in exercise of the Tribunal’s inquisitorial function.”
Although more difficult to establish, the doctrine of “Wednesbury unreasonableness” can also form a basis for a finding of jurisdictional error. A decision can be set aside if it is established that a decision maker reached a decision so unreasonable “that is might almost be described as being done in bad faith” or “so absurd that no sensible person could ever dream that it lay within the powers of [the decision maker]”69. The ground of unreasonableness can overlap with the ground that the decision maker took into account irrelevant, or failed to take into account a relevant, consideration70.