The 2015 amendments to the Citizenship Act introducing citizenship-stripping provisions for dual nationals (further amended in 2019) have long been considered by many constitutional lawyers to be unconstitutional - not to mention unedifying for a liberal democratic rule-of-law country. Now the High Court has determined that, in the case of section 36B at least, this provision is indeed unconstitutional.

A fundamental liberal democratic concept - the separation of judicial power - drove this result.

"(W)here the penalty for misconduct involves not only a loss of liberty within the community, but the loss of all entitlement to be both within the community and at liberty," the majority insisted on the strict safeguards. It is not within the minister's discretion to punish. This is reserved to the courts.

But identifying the rights of Australian citizens was also an important element of the judgement. The High Court affirmed that "[f]or an Australian citizen, his or her citizenship is an assurance that, subject only to the operation of the criminal law administered by the courts, he or she is entitled to be at liberty in this country and to return to it as a safe haven in need. These entitlements are not matters of private concern; they are matters of public rights of 'fundamental importance' to the relationship between the individual and the Commonwealth."

For all those stranded Australians during COVID, their entitlement to return to Australia as a safe haven was not ultimately reviewed by the High Court, but there are sentiments in this judgement ever alert to the need to ensure strict scrutiny of legislation that undermines fundamental rights. Get this wrong and the wait for a court to set things rights can be long indeed - if it ever comes. In this case, it took seven years for the High Court to rule on the constitutionality of citizenship-stripping through ministerial discretion.

The High Court's decision is also important for those Australian citizens stranded in refugee camps - including over 40 children. The Save the Children Fund has been urging the Australian government to ensure it not breach the Convention on the Rights of Children and enable these Australian children to be brought back to Australia with their stranded mothers.

The Citizenship Act continues to enable the government to strip dual citizens, and only dual citizens, of their Australian citizenship. It means that two Australian citizens can do exactly the same thing but only one of them, the dual citizen, risks losing their citizenship. Justice Edelman powerfully highlights this in his separate majority judgement, effectively encouraging the government and individuals to think further about other cases that may now be brought before the court to challenge the Citizenship Act's continuing powers to strip dual citizens of their citizenship in other ways.

Justice Edelman identifies how the Commonwealth's legislation, and the arguments used to defend it, have the likely consequence that potentially half of the permanent population of Australia are aliens - being dual citizens, by being born overseas, or having at least one parent who does not hold Australian citizenship.

"Almost by definition, something must have gone wrong in the application by this court of the meaning of the constitution for it to be concluded that the Commonwealth Parliament has power to legislate on the premise that potentially half of the people of the Commonwealth of Australia are foreigners to the political community of the Commonwealth of Australia," he writes.

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What does that power do to the social cohesion and equality of citizenship in Australia? As I have written elsewhere, it is undermining of a vibrant multicultural society to have half of our population vulnerable to being treated unequally, because they have more than one citizenship. This approach to dual citizens flows from an approach to citizenship since the time of the rise of terrorism that has used it as a framework for exclusion rather than as a vehicle for creating a more socially cohesive and robust and secure society.

This has permeated beyond the stripping of citizenship to other citizenship decisions reflecting poorly on our community - erring on the side of exclusion rather than inclusion. This mean-spirited approach is not reflective of the positive and meaningful ways Australia has been enhanced as a nation by those who acquired Australian citizenship.

Not only is the High Court decision constitutionally important, but it enables us to reflect once again, as matter of public policy, about how best to deal with terrorism in a Western liberal democracy that values the liberty of the individual. This is where criminal law and other provisions outside of citizenship law can properly be relied upon and pursued. It should not be about undermining our own Western liberal democratic commitment to protecting the liberty of the individual - to protecting citizenship - for if that occurs, then surely the terrorist's aim is partly fulfilled.

A review of the "Cessation of Citizenship" provisions - a term the High Court identified as a sanitised term for the draconian, punitive measure of depriving Australians of their fundamental rights, reaching to up to half of the population - is a necessary next step for this government, as a way of strengthening and protecting all Australian lives.