The case of LPDT v Minister for Immigration, Citizenship, Migrant Services and Multicultural Affairs [2024] HCA 12 concerned judicial review proceedings in the High Court of Australia (High Court) in which the High Court provided practical guidance about the threshold of materiality in the context of jurisdictional error.

The test for establishing jurisdictional error is two-fold. Firstly, it must be established that an error occurred and secondly, the error must be material such that the decision affected by error could realistically have been different if there was no error (see [30] and [32]). The practical guidance provided by the High Court in respect of this test is set out in this article.

The judicial review proceedings relevantly concerned an allegation that the decision of the Administrative Appeals Tribunal (Tribunal) in respect of a decision made under section 501CA(4) of the Migration Act 1958 (Cth) (Migration Act) about the revocation of a decision to cancel the Appellant's visa (Cancellation Decision) was affected by jurisdictional error.

There was no dispute that the Tribunal's decision involved an error because the Tribunal did not comply with a direction of the Minister in relation to the revocation of a mandatory cancellation of a visa under section 501CA (Direction) in breach of section 499(2A) of the Migration Act (at [30]).

In respect of the materiality of the error, the High Court held that the decision reached by the Tribunal could have been different if there was no error and thus the threshold of materiality was met (see [35] and [36]).

The High Court allowed the appeal, set aside the decision of the Full Court of the Federal Court of Australia, and ordered the issue of a writ of certiorari quashing the Tribunal's decision and a writ of mandamus directing the Tribunal to determine the Appellant's request for revocation of the Cancellation Decision according to law.

Jurisdictional error arises where a decision-maker with authority to make a decision under statute is in breach of an express or implied condition of the decision-making authority, such that the decision made lacks legal force and is "in law…no decision at all" (at [2]).

The High Court observed that the following categories of jurisdictional error often arise, but that the categories are not closed (at [3]):

• A breach by a third-party of a condition of a statutory process before a decision is made.

• A breach by a decision-maker given authority under statute of a condition of making a decision. Common errors in this context include: the decision-maker misunderstands the applicable law, asks the wrong question, identifies a wrong issue, ignores relevant material, relies on irrelevant material, exceeds the bounds of what is reasonable, denies a requirement of procedural fairness, or makes an erroneous finding or reaches a mistaken conclusion.

Not every breach of an express or implied condition of making a decision will render the decision no decision at all (at [4]).

The limits imposed by the relevant statute on the making of a decision must be understood to determine the following (at [4]):

• "…[W]hether an error has occurred (that is, whether there has been a breach of an express or implied condition of the statutory conferral of decision-making authority)..."

• "…[W]hether any such error is jurisdictional (that is, whether the error has resulted in the decision made lacking legal force)."

The High Court stated the following practical guidance in respect of the test for jurisdictional error:

• Both parts of the test start with a consideration of the statute to understand the nature of the alleged error in its statutory context (at [5]).

• Both parts of the test are backward-looking in that they are answered having regard to the decision that was made, and if necessary, how that decision was made (at [10]).

• Whilst the applicant has the onus of proof on the balance of probabilities, proving the facts ought not be difficult or contentious. In some cases the tendering of the decision-maker's reasons is sufficient, whereas in others, for example those involving an allegation of a denial of procedural fairness, may require evidence of the content or information required to be provided to the decision-maker (see [10] to [13]).

• To establish materiality, it is not necessary that absent the error a different decision "would" have been made, rather it is whether a different decision "could realistically" have been made. The High Court observed that "realistic" is used to distinguish a possible different outcome from an outcome that is fanciful or improbable (see [7] and [14]).

• The threshold of materiality is not onerous or demanding. What must be demonstrated to meet the threshold depends upon the error. A Court in determining whether the threshold is met must not assume the function of the decision-maker and fall into a merits review of the decision made (see [14] to [15]).

• Once the applicant establishes an error and that there is a realistic possibility of a different outcome if the error had not been made, the threshold of materiality is met and relief is justified subject to any utility and discretion (at [16]).

The High Court also observed that in some cases, such as those involving apprehended or actual bias, the alleged error will be jurisdictional regardless of any effect on the decision made, whilst in others, such as those involving unreasonableness, the potential for the decision to be effected is inherent in the nature of the error (at [6]). In both of these examples, the error satisfies the requirement of materiality.

The practical guidance from the High Court set out above overrides any previous guidance of the Courts (at [8]).

The High Court was satisfied that the threshold of materiality was satisfied in this case because the Appellant established on the balance of probabilities that a different decision realistically could have been made if the Tribunal followed the process of reasoning required by the Direction in deciding whether the Cancellation Decision should be revoked (see [34] and [35]).

The High Court allowed the appeal, set aside the decision of the Full Court of the Federal Court of Australia, and ordered the issue of a writ of certiorari quashing the Tribunal's decision and a writ of mandamus directing the Tribunal to determine the Appellant's request for revocation of the Cancellation Decision according to law.