In his final report last year as independent national security legislation monitor, Bret Walker, SC, recommended the government have the power to disown dual citizens involved in terrorism if it would not make them stateless.

Now the barrister and former president of the Law Council of Australia fears the government is going too far and is considering a regime that could be unconstitutional.

In particular, he is concerned that allowing the immigration minister, rather than the courts, to determine whether someone is a terrorist and revoking their citizenship on that basis leads to a very dark place.

Other legal experts have described it as “Kafka-esque”.

“They mustn’t do this,” Walker tells The Saturday Paper. “I really would like them to draw back and make it clear that of course they’re not talking about a ministerial parallel to a criminal process.”

“The people we’re talking about are not deterred by blowing themselves up … so they’re not going to be deterred by being deprived of citizenship.”

It is indeed a bizarre turn of events, when Malcolm Turnbull and conservative Liberal senator Cory Bernardi find themselves on a unity ticket against counterterrorism proposals being pushed by Tony Abbott and most of his backbench.

This week the government was divided over an issue that goes to the core of the power of government and the role in a democracy of the rule of law.

In the latest counterterrorism frenzy, the government will introduce legislation within weeks allowing the immigration minister, Peter Dutton, to strip dual nationals of Australian citizenship if they are involved in terrorism.

Even without seeing details of the legislation, Opposition Leader Bill Shorten has been goaded into expressing “in-principle support” for this measure, which extends existing laws that revoke citizenship if dual nationals join a foreign army that is fighting Australia.

Abbott wanted to go further and apply the measures to Australians who have no other citizenship but who might be eligible to apply elsewhere. On this, he was rolled by his cabinet last week. In an extraordinarily detailed leak of cabinet debate, The Sydney Morning Herald’s political editor, Peter Hartcher, revealed that six cabinet ministers had risen up against the proposal, with some warning that it trashed the rule of law and could leave people stateless.

Turnbull denied he had any hand in the leak, as did Foreign Minister Julie Bishop, as Machiavellian theories circulated about the source and whether it was designed to damage the prime minister or his rivals.

Turnbull went on to publicly opine, at a press conference on Wednesday, about the importance of the rule of law and its role in restraining the actions of government. On questions of national security, he said: “It is not good enough that laws simply be tough, this is not a sort of a bravado issue, it is that they have got to be the right laws”.

Bernardi went further, saying the proposal to allow a sole national to be stripped of citizenship at the whim of a minister was “the sort of power creep that I think is very dangerous from any government”.

Abbott was more concerned with instinct than the rule of law. “We know, instinctively, that anyone who raises a gun or a knife to an Australian because of who we are has utterly forfeited any right to be considered one of us,” he said in parliament, before demanding Labor declare its hand.

Most of the backbench rallied to support him, including some who had sought in February to end his leadership. Forty-four Coalition MPs in the house of representatives signed a petition urging him to extend the measures “not only to dual nationals, but those eligible for the citizenship of another country”. If this were adopted, even Australians with no other citizenship could lose it and end up refused re-entry to Australia or detained here indefinitely.

When Liberal backbenchers handed around the petition in question time last Thursday, they did not bother to ask Philip Ruddock for his support. Ruddock, known as Father of the House because he is the longest-serving MP, would not have signed it anyway.

He argues it would be inappropriate, as he is supposed to be jointly leading a national conversation on these matters, in his new role as the PM’s special envoy for citizenship and community engagement. He says he does not come to this role with preconceived views.

However, he does believe that laws to revoke citizenship could deter some would-be terrorists.

“We’re making sure people understand, when they become Australians, there is a commitment to accept and honour the laws of Australia and there are consequences if you don’t,” he tells The Saturday Paper.

“Those consequences may be jail but they may also be, for some, deprivation [of citizenship]. And I’m saying, in my view, it is not unreasonable to assume that some people might be influenced by that and, if they are, I think that is a good thing.”

Ruddock invokes the rule of law, but rather than Turnbull’s notion of it as a limit on government power he characterises it as something that those who take Australian citizenship must respect. “I think deprivation is about focusing people’s minds on why it is undesirable to not observe the rule of law,” he says.

According to Hartcher’s detailed reports, several cabinet ministers felt the proposals pushed by Dutton, with Abbott’s backing, would undermine the rule of law.

He wrote that Barnaby Joyce, George Brandis, Christopher Pyne, Turnbull and Bishop all raised objections, and Kevin Andrews warned that targeting sole nationals would be even more controversial in the community than in cabinet.

Although Walker argues there are valid national security reasons for revoking dual citizenship, he rejects the suggestion it is a deterrent.

“We can put safely to one side all thought of deterrent value,” he says. “The people we’re talking about are not deterred by blowing themselves up or being shot down by jet fighters, so they’re not going to be deterred by being deprived of citizenship.”

Curtin University researcher and counterterrorism expert Anne Aly goes further, saying the measures play right into the hands of the terrorist movement, which entices people with the promise of citizenship of a new Islamic State.

“They want people to go there and become stateless,” she says. “That’s what they’re banking on. They are building their state with the lost souls of those who have been lured into their web and find no escape. Why we would want to give them that is beyond me.”

She also warns that the discourse around citizenship-stripping could risk inflaming tensions and fuelling feelings of isolation and disenchantment for some Australian Muslims.

“Hopefully the government will be smart about this and will not frame this in a way that only further contributes to an already tense and volatile relationship between the government and the Australian Muslim communities that they are also elected to represent,” says Aly.

The cabinet split forced Abbott to ditch plans to legislate that sole nationals could be targeted and instead incorporate this into a discussion paper. He has appointed Ruddock and parliamentary secretary Concetta Fierravanti-Wells to oversee consultation on the measures and on citizenship more broadly.

Ruddock, a former attorney-general and immigration minister, is a curious mix of national security hawk and champion of multiculturalism and inclusion. It was the more dovish side that surfaced in one debate this week.

Liberal MP Andrew Nikolic, who was promoted to the Coalition whips team when Ruddock was shafted from it in February, moved a rather bellicose motion supporting the government’s approach to national security, no doubt designed to pressure Labor. Ruddock seconded the motion. Some MPs who spoke on it gave in to the urge to thump their chests about the threat of terrorism, but Ruddock struck a different tone. He argued the numbers of people involved were relatively small and “we ought not to allow ourselves to demonise whole communities because of the actions of individuals”.

At this stage, Ruddock won’t say whether he considers stripping sole nationals of citizenship to be warranted or legal. But he does imply there are good arguments for it, suggesting terrorists might renounce claims to citizenship elsewhere if being a sole national ensures their Australian citizenship cannot be revoked.

He also tackles another controversial dimension of the proposals, mounting the case for the immigration minister, rather than the courts, having the power to decide if someone loses their citizenship.

“With terrorism, there is difficulty getting what I regard as normal admissible evidence,” he says. “Very often, you are reliant upon intelligence and the difficulty with intelligence is that, if you put it into the public arena, particularly even informing the individual about whom you have concerns, you are exposing the very people who might help inform you.”

This argument worries Walker.

“It’s just not good enough to say that conviction is difficult,” says Walker. “Well, yes, so it is, but why on earth would you say, ‘We are going to pass laws to permit people to be punished in advance of, indeed without even trying to, convict them’? What an extraordinary thing to say about the rule of law.”

Walker adds that giving the minister this power could be unconstitutional, as revoking citizenship would be punitive. Under the constitution, only a court can rule on punishable offences. Conviction for Commonwealth offences requires a judge and jury.

Kim Rubenstein, the director of the Australian National University’s centre for international and public law, says any citizenship revocation proposals, whether of dual or sole nationals, would certainly face legal challenge.

“There would be a very strong case that it’s beyond the power of the Commonwealth to strip individuals of their citizenship,” she says. “This potential change is a reversion back to a notion of subjectivity in terms of the power of the state, which I think is very unhealthy in terms of the rule of law democratic framework.”

Constitutional lawyers have also flagged that a compromise put forward by the minister for social services, Scott Morrison, to suspend certain citizenship rights, would clash with High Court rulings enshrining the rights of citizens to enter and remain in Australia.

Walker says the current debate about citizenship-stripping falls into a category of lawmaking he describes as primarily designed to “encourage a kind of mutual pretence between the government and some people and some commentators that something is being done about something which is deplorable”.

But he fears that the rhetoric could backfire. “It is glamorising and rendering more important than they really are the adherents to and supporters of these dreadful terrorist movements. You only have to follow the inquest into Monis [the Lindt cafe hostage-taker and murderer] to know how dangerous all that can be.”

Australia is not alone in considering banishing those who support IS. The model being pushed by backbenchers and by Abbott resembles a recently enacted British regime, with broad ministerial discretion. New laws in Canada give the minister power to revoke citizenship, but only on the basis of a conviction.

Professor of law at the University of Toronto Audrey Macklin writes in a recent publication that denationalisation has long been a tool used by states “to rid themselves of political dissidents, convicted criminals and ethnic, religious or racial minorities”.

“The latest target of denationalisation is the convicted terrorist, or the suspected terrorist, or the potential terrorist, or maybe the associate of a terrorist. He is virtually always Muslim and male,” writes Macklin.

“Citizenship-stripping is sometimes defended in the name of strengthening citizenship, but it does precisely the opposite. The defining feature of contemporary legal citizenship is that it is secure. Making legal citizenship contingent on performance demotes citizenship to another category of permanent residence. Citizenship revocation thus weakens citizenship itself. It is an illegitimate form of punishment and it serves no practical purpose.”

For Abbott, it may have already served its practical purpose. He has posed as “instinctively” tough on terrorism, tougher indeed than his leadership rivals. He has issued a veiled threat to cabinet ministers that leaking has “political and personal consequences”. He has rallied backbenchers around him and forced Labor to pre-emptively declare “in-principle” support for laws it is yet to see.

Talking terrorism makes Abbott feel secure and it’s a theme on which he will continue to focus. But he still has to deal with a deeply divided cabinet.