This matter involved the applicability of ‘aliens’ under s 51(xix) of the Australian Constitution (1901) (Cth) to Indigenous Australians. The majority (4:3) determined Aboriginal Australians (or Aboriginal and Torres Strait Islander peoples) could not be considered aliens, and that the Commonwealth lacks constitutional power to deport Aboriginal persons under the Migration Act 1958 (Cth). This is a question that has never been tried before. The High Court reaffirmed the continued unique cultural, historical and spiritual connection that Indigenous peoples have to country or ‘the territory of Australia’ regardless of whether or not they were born here or hold citizenship. The decision was the result of two cases heard together, concerning Brendan Thoms and Daniel Love.
Thoms, a descendant and elder of the Gunggari People, was born in New Zealand. Love, a descendant of the Kamilaroi tribe and recognised by a Kamilaroi elder, was born in Papua New Guinea. Both the Gunggari and Kamilaroi peoples are native title holders. Thoms and Love lived in Australia under non-permanent visas, were sentenced for offences under the Criminal Code (Qld), and their visas were consequently cancelled. As the plaintiffs had Indigenous ancestry, identified as Aboriginal and Torres Strait Islander peoples and were accepted by their Indigenous communities, they satisfied the tripartite test of Aboriginality developed by Brennan J in Mabo v Queensland [No 2]  HCA 23 (Mabo (No 2)). The question in dispute was whether non-citizen Aboriginal Australians could be deported as aliens under the constitution generally. The court did not determine the citizenship nor Aboriginality of the particular plaintiffs.
The plaintiffs did not question their citizenship status. Their main argument was that, as Aboriginal Australians, they have special status as non-citizen, non-aliens, flowing from the connection Aboriginal people have to country. Hence, Indigenous Australians can only belong to Australia. This connection is recognised by the common law, so categorising an Indigenous Australian as an alien would be inconsistent with this. The plaintiffs contended the Crown owes Indigenous Australians permanent protection to maintain this connection, challenging the validity of Australian Citizenship Act 2007 (Cth). Also deportation is inconsistent with the enjoyment of native title rights and interests.
The Victorian government intervened to support the plaintiffs arguing that Aboriginality is equivalent to citizenship. . They concurred that the unique relationship between members of Aboriginal societies and the land and waters of Australia meant that Aboriginal Australians are not captured by s 51(xix).
The Commonwealth contended s 51(xix) confers the power to determine who is an alien. The Australian Citizenship Act 2007 (Cth) validly does this by providing a definition of an alien as any persons born overseas, which captured the Plaintiffs. The Commonwealth disputed an implied constitutional limitation, especially one based on race. They also argued that alien status is based on connection to the sovereign, connection to land is irrelevant. The Commonwealth submitted overall the matter was a statutory, rather than constitutional, question. As the plaintiffs lacked citizenship under the valid act, deportation was possible.
Bell, Nettle, Gordon and Edelman JJ found that Parliament did not have the power to treat an Aboriginal person as an ‘alien’, given the common law recognition of native title. This involved analysis of the definition of ‘alien’, which indicates ‘belonging’. Subsequently, s 51(xix) does not extend to treating an Aboriginal Australian as an alien, as an Aboriginal Australian cannot ‘belong’ to another place. Gordon and Bell JJ reaffirmed the sui generis position of Aboriginal Australians in this Australia.
This decision was based on Mabo (No 2), a decision which highlighted the ‘deeper truth’ that Indigenous Australians are the first peoples, and the connection to Australia has never been severed. The common law hence has a ‘unique obligation of protection owed by the Crown to those societies and to each member in his or her capacity as such’ to permanently protection a resident non-citizen Aboriginal ().
In the decision, their honours emphasised the connection Indigenous Australians have to country. Nettle J found that it would be inconsistent for the common law to recognise connection to country and exclude those holding this connection. At , his honour held this connection is ‘a matter of history and continuing social fact, an Aboriginal society’s connection to country is not dependent on the identification of any legal title in respect of particular land or waters within the territory.’ Edelmen J stated the connection to Australia is one indissoluble whole and, at , the ‘loss of native title rights to land and loss of relationship with particular land does not extinguish the powerful spiritual; and cultural connections.’
In relation to the tripartite test, it was rejected that Aboriginal Australians would have the choice to determine alienage or that this would create uncertainty. Overall, the decision meant that the Migration Act 1958 (Cth) must be read down to exclude application to Aboriginal Australians. The limitation placed on 51(xix) was deemed appropriate based on the common law recognition of native title rights and interests. Contemporary understanding.
Kiefel CJ, Gageler and Keane JJ disagreed with the majority in separate judgments, mostly in regard to whether Mabo (No 2) was relevant to interpreting the Constitution.
Their honours held constitutional limitations should not be made lightly. They found no textual basis to do so in the limitation and should not be made in this case. Both Justice Gageler and Justice Keane especially had concerns over a race based limitation.
Further, the dissenting judges variously held that the Plaintiff’s arguments were legally unsustainable. It was stated that the connection Mabo (No 2) recognised is legally limited to native title law, and geographically limited. The connection Indigenous groups have is specific to particular lands, rather than a unified connection to Australia as a whole. Acknowledging its importance, Kiefel CJ reaffirmed that common law recognition of native title which has survived the acquisition of sovereignty but held this cannot be extended to [maybe add a direct quote]. Further, customs provide evidence of connection to country, but are not recognised themselves by the common law. The Plaintiffs submission that the Crown owes special protection to Indigenous Australians was also rejected.
Kiefel CJ concurred that the Aboriginality test would impermissibly allow elders to determine who is a non-alien. Keane J agreed this would create dangerous uncertainty, given that alien is the legal relationship to a nation by the individual, not to a cultural grouping. Both reiterated native title’s vulnerability, and that Indigenous sovereignty was implicitly rejected in Mabo (No 2) through the possibility of extinguishment.
The dissenting judges was concluded that Aboriginal Australians can be aliens. As the Plaintiffs were not citizens under valid legislation enacted under 51(xix), they were aliens and could be deported.