Minister for Immigration, Citizenship, Migrant Services and Multicultural Affairs v Thornton

The Minister for Immigration, Citizenship, Migrant Services and Multicultural Affairs (the Minister) appealed to the High Court of Australia from a decision of the Full Federal Court. The dispute concerned the lawfulness of the Minister's decision to refuse to grant a protection visa to Mr. Thornton, a citizen of the United Kingdom. Mr. Thornton had arrived in Australia by boat and claimed to fear persecution in the United Kingdom due to his alleged involvement with a terrorist organisation. The Minister had refused the visa on the grounds that Mr. Thornton did not meet the criteria for a protection visa, including the requirement that he not be a person about whom there was a danger to Australia.

The High Court was required to determine whether the Minister's decision to refuse the protection visa was vitiated by jurisdictional error. Specifically, the Court considered whether the Minister had failed to consider relevant considerations or taken into account irrelevant considerations when assessing whether Mr. Thornton posed a danger to Australia, as required by the *Migration Act 1958* (Cth). The central question was whether the Minister's assessment of the risk posed by Mr. Thornton was so unreasonable that it could not be justified by the evidence before him, thereby constituting a failure to exercise the power conferred by the Act according to law.

The Court held that the Minister's decision was affected by jurisdictional error. Gageler, Gordon, Edelman, Steward and Jagot JJ reasoned that the Minister's assessment of the risk posed by Mr. Thornton was based on a misunderstanding of the evidence and a failure to engage with the specific findings of the Australian Security Intelligence Organisation (ASIO). The Minister had, in effect, substituted his own assessment of the risk for that of ASIO, without a proper basis for doing so. This failure to properly consider the evidence and the findings of ASIO meant that the Minister had not exercised his power lawfully. The Court therefore allowed the appeal and set aside the decision of the Full Federal Court, remitting the matter to the Federal Court for redetermination.