Plaintiff M61-2010E v Commonwealth of Australia & Ors

The High Court of Australia heard an application for leave to appeal and an appeal concerning the detention of the applicant, identified as Plaintiff M61-2010E, a citizen of Sri Lanka. The respondents were the Commonwealth of Australia and various ministers and departments. The dispute centred on the lawfulness of the applicant's detention, which had commenced upon his arrival in Australia by boat and continued following his transfer to Nauru under a regional processing arrangement. The applicant sought a declaration that his detention was unlawful and an order for his release.

The central legal issue before the Court was whether the detention of the applicant, a non-citizen who arrived unlawfully in Australia, was authorised by law. Specifically, the Court had to consider the scope and effect of section 189 of the *Migration Act 1958* (Cth), which mandates that unlawful non-citizens must be detained. The Court also had to determine whether the executive government had the constitutional power to detain the applicant in Nauru, given that such detention occurred outside Australian territory.

The Court, in a joint judgment, held that section 189 of the *Migration Act* validly required the detention of the applicant. However, the Court found that the executive government did not possess the constitutional power to detain the applicant in Nauru. This conclusion was based on the principle that the executive power of the Commonwealth, as conferred by section 61 of the Constitution, does not extend to the detention of persons outside Australia in the absence of specific legislative authorisation. The Court reasoned that detention is a significant deprivation of liberty and requires clear statutory authority, which was lacking for detention on Nauru.

Consequently, the High Court granted leave to appeal, allowed the appeal, and ordered that the applicant was not lawfully detained. The Court declared that the applicant was entitled to be released from detention.