Among the most highly controversial subjects today is how one determines who is an Aboriginal person and whether Aboriginal people should be treated differently to other groups under the law and the constitution.

The High Court's judgment in the Love and Thoms cases dealt directly with these issues, and like the general public, the court was on some points fiercely divided.

The case concerned the Federal Government's intention to rely on provisions in the Migration Act to deport from Australia, on character grounds, two men who had been convicted of criminal assaults.

Both were born outside Australia and were not Australian citizens, but each had spent most of their lives in Australia.

The Migration Act is based on the Commonwealth's power to make laws with respect to 'aliens'.

Brendan Thoms and Daniel Love argued that as they were Aboriginal people, they could not be regarded as aliens, so the act did not apply to them and they could not be deported.

How do we define who is Aboriginal?

On the first issue of determining Aboriginality, the court showed unanimous acceptance of the earlier tripartite definition that had been used in the Mabo case.

Eddie Mabo endured a decade-long legal fight. ( Supplied: Gail Mabo )

To be regarded as an Aboriginal person, a person must be biologically descended from Aboriginal people, self-identify as an Aboriginal person and be recognised as a member of an Aboriginal group by its elders or those with traditional authority to determine its membership.

In this case Mr Thoms clearly satisfied that definition. Even though he had been born in New Zealand, he was a descendant of the Gunggari people and self-identified and was recognised as such. He had already been recognised at law as a native title holder.

The position of Mr Love was less clear.

While born in Papua New Guinea, he was descended from the Kamilaroi people and recognised as such by one elder, but it was not clear whether this was sufficient.

Further facts were required and the matter was referred to a lower court.

While the justices were generally agreed on these definitional issues, both Chief Justice Susan Kiefel and Justice Stephen Gageler raised concerns that this meant that the legal status of a person would be determined by elders or others of a particular group, who may not be representative or accountable.

Chief Justice Kiefel saw it as attributing a kind of sovereignty to the group, which had been rejected in the Mabo case.

Daniel Love with his son. ( Supplied )

Can an Aboriginal person be an alien?

On the issue of whether an Aboriginal person, who is not an Australian citizen, can be treated as an alien, the court split by four to three. Each judge wrote a separate judgment, which together ran to 169 pages.

The four judges in the majority — Justices Virginia Bell, Geoffrey Nettle, Michelle Gordon and James Edelman — reached their conclusions by different reasoning.

Accordingly, it is very difficult to draw from the judgments clear majority propositions.

Justice Bell stated at the end of her judgment:

"I am authorised by the other members of the majority to say that although we express our reasoning differently, we agree that Aboriginal Australians (understood according to the tripartite test in Mabo [No 2]) are not within the reach of the "aliens" power conferred by s 51(xix) of the Constitution."

The majority judges focused upon the strong connection of Aboriginal people with their traditional lands and waters, noting that it was not only a legal connection, but also a spiritual, cultural and religious one.

The Aboriginal flag flies at the Garma festival in Arnhem Land. ( ABC: Mitchell Woolnough )

Because the common law recognises their unique connection with Australian lands and waters, they must be regarded as 'belonging' to Australia and therefore cannot fall within the meaning of 'alien' as used in the Constitution.

Justice Nettle went further, arguing that the Crown owes a unique obligation of protection to Aboriginal people and that in return, they owe permanent allegiance to the Crown.

The Crown's obligation of protection included not casting out Aboriginal people from Australia as aliens.

Such a view, if taken up by the majority in the future, could result in many further obligations being identified, on both the government and indigenous sides.

Justice Patrick Keane, however, rejected the notion of 'permanent allegiance' as a paternalistic approach that potentially limits the autonomy of persons of Aboriginal descent. He argued that this was not consistent with fundamental notions of equality before the law.

The case explores the idea of 'belonging'

Overall, the minority judges, Chief Justice Kiefel and Justices Gageler and Keane, had trouble connecting the distinct property rights of native title holders to a particular area of land with membership of the Australian body politic. Chief Justice Kiefel saw this as involving different types of belonging.

An Aboriginal person can belong to their traditional land in one sense, but this is different to a citizen belonging to a country.

Justice Keane saw the problem as confusing property rights with citizenship rights.

An alien can own land in Australia, and the land will 'belong' to him or her, but the alien will still 'belong' to the country of which he or she is a citizen and must get a visa to enter Australia to visit his or her land.

Can Australian citizenship now be based on race?

One of the most controversial issues was whether this decision would place a race-based distinction in the constitution.

Chief Justice Kiefel said that "race is irrelevant to the questions of citizenship and membership of the Australian body politic".

Justice Gageler stated that he objected in principle "to the judicial creation of any race-based constitutional distinction irrespective of how benign the particular distinction contended for might seem".

He was concerned that the potential political and societal ramifications of the judgment could not be judicially appreciated and that the viewpoints of representative Aboriginal bodies had not been put to the court on these issues.

Justice Bell responded that it "is not offensive … to recognise the cultural and spiritual dimensions of the distinctive connection between indigenous peoples and their traditional lands, and in light of that recognition to hold that the exercise of the sovereign power of this nation does not extend to the exclusion of the indigenous inhabitants from the Australian community".

Justice Gordon pointed out that the constitution "does not prohibit special treatment of a race", as the "race power" expressly provides for it.

She noted that such a power might be exercised in response to historical considerations or current disadvantage.

Justice Edelman added that equality before the law does not mean treating differences as though they are alike.

Where there is a relevant difference, such as the existence of a unique and legally recognised connection to land, this must be recognised and accommodated.

These responses all show that these issues, which vex the community at large, are also disputed among those who hold the highest offices in the land.

While the judgments in the Love and Thoms case will have a relatively narrow direct effect — only protecting Aboriginal non-citizens from deportation — the broader ramifications of the court's analysis of the connection of Aboriginal people to their land and waters will take decades to resolve.