The persistency with which these two separate jurisdictional errors continues to be conflated by the Minister deserves calling out.
Justice Perry did so in BMW16 v Minister for Immigration and Border Protection  FCA 1036 at :
A finding may taint a decision with jurisdictional error in cases where a particular finding is not open on the evidence, even though it cannot be said that there is no evidence on the point.
One would have thought this was obvious, despite attempts to constrain the meaning and operation of s 473DD and excessively defer to the IAA. The High Court has now confirmed that proposition. In ABT17 v Minister for Immigration and Border Protection  HCA 34 at  the plurality said:
.. The new information so got by the Authority would then meet the preconditions to its consideration by the Authority on the basis that it was not and could not have been before the Minister when the delegate made the referred decision and on the basis of the Authority's satisfaction that the existence of any informational gap is sufficiently aberrant within the scheme of de novo review for which Pt 7AA provides to make existence of the informational gap in the particular review alone enough to constitute "exceptional circumstances" justifying its consideration irrespective of how frequently such an informational gap might arise in practice.
The proposition to the contrary, that there is a requirement for illogicality or irrationality to also be ‘extreme’, is made by the Minister with alarming frequency and betrays an understanding of what exactly is required to make out a jurisdictional error of this kind.
In AWU16 v Minister for Immigration and Border Protection  FCA 513 the Federal Court said:
 Referring to CQG15 v Minister for Immigration & Border Protection  FCAFC 146; 253 FCR 496 at , the Minister submitted that the alleged illogicality or irrationality of reasoning must be of an “extreme” kind, not a matter on which reasonable minds might differ, and not a matter on which a supervising Court simply disagrees with a decision-maker, even emphatically.
 Save for the gloss arising from the word “extreme”, those propositions can also be accepted and are well established. There is nothing in High Court authorities such as Minister for Immigration and Citizenship v SZMDS  HCA 16; 240 CLR 611 which suggests that the adjectival description of “extreme” is a necessary element in a finding of illogicality or irrationality. If the decision-maker’s fact finding is proven to be irrational or illogical, in a way which was material to the outcome of the review, that is sufficient. The stringency of the threshold arises in the need for the decision-maker’s reasoning to be capable, objectively, of being described as irrational or illogical.
In Chamoun v Minister for Immigration, Citizenship, Migrant Services and Multicultural Affairs  FCAFC 66, Mortimer and Bromwich JJ said:
 If the Minister understood he could seek further information from the appellant, in the context of the importance and weight he attached to the plainly adverse NSW Police Report, then acting reasonably and rationally there was, we are satisfied, a realistic possibility he may have sought further information because the Minister had no information at all about what the appellant’s response to the content of that report might be. We are not required to be satisfied it is more likely than not he would have exercised the power he did not appreciate he had, only that there is a realistic possibility he might have. In our opinion, the adjective “realistic” in the statements of principle by the majority in the High Court in Hossain and Minister for Immigration & Border Protection v SZMTA  HCA 3; 364 CLR 421 is used to distinguish the assessment of the possibility of a different outcome from one where the possibility is fanciful or improbable, no more than that.
This bootstrap reasoning is common in decisions which read as if the decision-maker knows he or she has no intellectually-defensible way of rejecting inconvenient corroborative evidence, and so resorts to dismissing it because of some kind of domino effect arising from the rejection of the original evidence of the applicant. In BZD17 v Minister for Immigration and Border Protection  FCAFC 94; 263 FCR 292 at  the Full Court explained that this kind of reasoning may be illogical:
… it is true that the High Court held in S20/2002 that it is not irrational (albeit not necessarily preferable) for the finder of fact to focus “first upon the case as it was put by the appellant”, before considering the alleged corroboration. However, this does not mean that the finder of fact can ignore the allegedly corroborative material and fail to consider it in an intellectually active way (WAIJ v Minister for Immigration & Multicultural & Indigenous Affairs  FCAFC 74 at  (Lee and Moore JJ); semble SZDGC at  (Finkelstein J)). For example, as in DAO16, a finding that a visa applicant’s evidence is not credible may not of itself provide a logical or rational basis on which to dismiss all of the corroborative evidence and, once the corroborative evidence is considered, it may at least raise a doubt about whether the whole of an applicant’s claims should in fact be rejected, thereby enlivening the obligation to consider the alternative scenario that the applicant’s claims might be correct.
In Asaad v Minister for Home Affairs (No 2)  FCAFC 214 the Full Court explained the interaction of estoppel and public law duties.
Care however must be taken to not interpret the Court’s observations as laying down a blanket rule that it will always be lawful for a Minister to revisit the exercise of a discretion. For example, when it is the re-exercise of the discretion in relation to the same set of facts, it may be that the subsequent exercise is unlawful as an abuse of process, or an exercise of the duty for an improper purpose, or otherwise invalid because of bad faith. Assad does not preclude these conclusions in the appropriate scenario.
In DQQ17 v Minister for Immigration and Border Protection  FCA 784 at , Colvin J said:
a submission by counsel appearing for the Minister that a decision under appeal is not attended with any doubt, or sufficient doubt or error must reflect the independent judgment of counsel after considering all of the materials in performance of counsel’s paramount duty to the Court. It is not to be based upon the lack of particularisation of grounds by an appellant who is appearing in person.
The contention to the contrary is still sometimes agitated by the Minister, but that is plainly wrong. If authority is needed, see ARG15 v Minister for Immigration and Border Protection  FCAFC 174 at :
… Illogicality or irrationality in that extreme sense may be considered not only in relation to the end result, but also extends to fact finding which leads to the end result, albeit that, as Robertson J emphasised in SZRKT at , the overarching question is whether the decision was affected by jurisdictional error (see also the observations of Beech-Jones J in BKE v Office of Children’s Guardian  NSWSC 523 at  and the cases referred to therein).
If there was ever a need for authority for the proposition that what an applicant says or writes is still ‘evidence’, and that there is no legal requirement for evidence to be corroborated before it can be accepted (and the increasing trend in Tribunal and IAA decisions suggests there is such a need), see NAKD v Minister for Immigration & Multicultural & Indigenous Affairs  FCAFC 321 per Hill J at .
A particularly egregious example of unreasonableness is Abboud v Minister  FCA 185 in which the Tribunal made arbitrary assumptions as to how a gay person ought to behave. The Tribunal has now on several occasions rejected persecution claims on the basis of sexuality through means of suggesting the applicant is involved in a gay ‘conspiracy theory’. Patently, such approach is unreasonable, irrational or demonstrative of failing to engage with the material before it. The entire Abboud decision is worth reading in order to expose the audacity of the Tribunal’s reasoning, but see especially -.