Home Affairs Minister Peter Dutton may soon gain retrospective powers to banish people he believes are dual citizens who have failed to uphold the nation’s values – without needing to provide proof.

Though aimed at those with terrorist links, the powers could be used against others who once served in a foreign fighting force, whether by choice or not – including refugees from Iraq, Afghanistan and elsewhere.

An open-dated reference to serving in countries with which Australia has been at war appears to create that possibility, according to legal experts.

Like the current citizenship cessation law, the legislation affects people aged 14 and over. The changes are designed to overcome serious problems with the existing law, which strips some dual nationals of Australian citizenship automatically for engaging in terrorism-related conduct or travelling to declared terrorism hotspots. This is the third version drafted in four years.

However, eminent lawyers have told The Saturday Paper it doesn’t resolve all of the problems – and potentially creates more.

Under the current law, citizenship can be stripped automatically without the government making active decisions on individual cases. The Australian government may not know who has lost their citizenship – when or where. Thus, it can’t know who is entitled to consular assistance overseas or any other services or protections available to Australian citizens.

Complicating matters, the Home Affairs minister doesn’t have to notify an individual that they have been stripped of their citizenship, if operational security could be compromised.

Under the latest changes, the minister would have the personal power to actively strip citizenship, case by case, from people whose conduct is deemed “incompatible with the shared values of the Australian community”. Such people are deemed to have “severed that bond and repudiated their allegiance to Australia”. It doesn’t define those common values.

Introducing the legislation, Dutton told parliament: “In recognising and protecting this unity and cohesion, it is essential that we continue to monitor, update and amend the way in which we deal with those who would threaten it. Behaviour that harms, or seeks to harm, our community – whether that be in Australia or offshore – is in clear opposition to the common bond and shared values that underpin membership of the Australian community.”

Two categories of people would be affected: those convicted of a relevant offence – sentenced to three years in jail, down from six – and others who spark security concerns.

Dutton need only be “satisfied” someone is a dual national and has entered a declared terrorist zone or is involved in banned groups or activities – in Australia or overseas.

The new version no longer insists those be proved as fact.

However, rendering a person stateless breaches international law, so the government must be sure someone qualifies for another nationality before revoking citizenship.

As a back-up, it legislated earlier this year to allow the temporary exclusion from Australia of some dual nationals fighting overseas.

The legislation lists “public interest” criteria the minister must consider – including the severity of a person’s conduct and level of threat, their connections to another citizenship country, their age and, for children, their best interests.

Dutton must also consider Australia’s international relations.

But there is a disincentive in the revocation system to actively check a person’s nationality, because it would alert other countries that might remove their citizenship first, leaving Australia solely responsible.

Former independent national security legislation monitor Bret Walker, SC, suggests this could cause problems.

“It will lead to some pretty distorted judicial review,” he says.

Walker says active ministerial decision-making significantly improves the existing automatic system, which he calls “bizarre”. But he queries whether this is the way to manage security challenges created by citizens joining terrorist groups overseas – about 230 people since 2012 and 80 at present.

“Are you really sure that this is how Australia should be giving effect to its anti-terrorist obligations?” he asks. “Will this really assist in Australia’s security against terrorism to keep these people out of the country?”

Australia is among those countries seeking to stop foreign fighters from coming home, despite the United States urging nations to allow citizens back and prosecute them.

Walker argues Australia should not be racing to strip a person’s citizenship ahead of another country, like “some ghastly, creepy musical chairs”. But his key concern is how hard it may be to persuade courts to overturn ministerial decisions.

While the satisfaction test avoids Dutton having to act like a court and rule on criminal offences, other problems arise if his decisions go before the Federal Court or the High Court for review.

Walker says the courts may be able to rule only on “whether it is legally open to the minister to be satisfied” – not on whether a person is actually a dual citizen or engaged in the barred conduct.

The assurance of review is “much more apparent than real”, he warns. “It’s not easy to envisage the court actually finding that conduct did not occur in fact or finding that dual citizenship [does not exist] in fact,” Walker says.“Increasingly, minister decision-makers don’t want the facts checked by the courts. They just want their state of satisfaction checked by the courts. They may be satisfied on a balance of probabilities but that balance of probabilities doesn’t make something true.”

Citizenship law expert and Australian National University professor Kim Rubenstein disagrees, arguing the wording elsewhere in the bill presumes the courts can make findings on the facts regarding conduct and citizenship. “It’s ‘the court finds’,” she says, “not ‘the minister finds’.”

Walker agrees the wording provides “a degree of comfort” but believes “there’s not much reassurance”.

Rubenstein criticises the bill’s onus on individuals taking the matter to court to prove the minister wrong. “There is some comfort that you must be a dual citizen for this to apply,” she says. “But the only way you can guarantee that is if you go to court, and the practical hurdles in this regard may be insurmountable.”

She doubts citizenship removal is needed to address security threats. “My belief is that the criminal law system sufficiently deals with that and that the Citizenship Act doesn’t add sufficient value to outweigh the real risks that come from using it.” She says those risks include disrupting social cohesion and making dual nationals second-class citizens.

Rubenstein also fears the slippery slope – future governments adding new offences based on a vague, legislated values statement. She says “other examples of socially unacceptable behaviour” could be included in future. “It hearkens back to our convict origins of removing from society those convicted of criminal offences.”

Asked if the clause on past war service could apply to refugees conscripted into foreign armies, Rubenstein says: “It is unclear what the consequences of the changes in both the timing and the interpretation of being at war with Australia mean in relation to individuals who have come to Australia in a variety of contexts – including as refugees – who may potentially fall under that provision.”

Bret Walker says it could affect refugees, and human rights lawyer and Australian Lawyers Alliance spokesman Greg Barns shares that view. “It’s so broadly drafted – and it’s clearly retrospective – that it could catch persons now living in Australia who previously had some association in Iraq or Afghanistan with those [who opposed] American-led forces,” Barns says.

He believes the changes vest “extraordinary discretionary power” in the Home Affairs minister. “The decision of the minister in some circumstances may be based on errors of fact, based on bureaucratic mistakes,” he says. “Given the seriousness of the consequences, it is inappropriate that such a decision can be made at the discretion of the minister. Only once the relevant allegations have been properly tested in an independent court or tribunal should there be any exercise by the minister of such a discretionary power.”

Peter Dutton initially wanted to strip sole Australian nationals of their citizenship in 2015 but federal cabinet threw out the proposal. Subsequent legislation affects only dual nationals.

But a procession of highly qualified lawyers has testified to its problems, not least that it could be unconstitutional.

Last week, the current Independent National Security Legislation Monitor, Dr James Renwick, recommended urgent amendment. He said the existing law operated in an “uncontrolled” and “uncertain” manner and lacked review rights and oversight.

The day after the government presented an unclassified version of Renwick’s report to parliament last week – a month after receiving it – the new citizenship bill was introduced.

Not addressed in it are Renwick’s concerns at the lack of formal oversight of the backroom advising process and the risk that stripping citizenship could actually prevent prosecutions and increase the security threat.

In a recent submission to the powerful parliamentary joint standing committee on intelligence and security (PJCIS), the Australian Security Intelligence Organisation made similar warnings. “In some instances, citizenship cessation will curtail the range of threat mitigation capabilities available to Australian authorities,” ASIO’s submission says. “It may also have unintended or unforeseen adverse security outcomes – potentially including reducing one manifestation of the terrorist threat while exacerbating another.”

The Australian Federal Police fears it could thwart prosecutions. “This can create a challenge for law enforcement,” the AFP submission said. “For example, some terrorism-related offences … only apply to Australian citizens.” The AFP also said this could potentially affect 23 outstanding arrest warrants for Australians overseas.

ASIO told The Saturday Paper that the proposed changes provide scope to “advise against citizenship cessation in circumstances where the outcome would be prejudicial to security or where the security risk could be better managed utilising other options”. Stripping citizenship was one protective tool “but it does not necessarily eliminate the threat posed by those who are subject to citizenship cessation”.

Dutton’s citizenship decisions would be based on advice from an existing multi-agency committee – the Citizenship Loss Board – convened by his departmental secretary, Mike Pezzullo.

Watchdog bodies have warned the board currently operates without formal oversight. Its hybrid structure means those bodies can’t examine it.

The bill widens the law’s scope, backdating it beyond 2015 to May 29, 2003, when another key piece of counterterrorism law was enacted, and making it retrospective.

The minister’s satisfaction test aims to provide extra legal protection for the government and avoid a repeat of the controversial case of Australian foreign fighter Neil Prakash. The government moved to strip Prakash of his Australian citizenship, arguing he was also Fijian. The Fijian government subsequently said he was not. The Department of Home Affairs still considers Prakash was Fijian at the time his Australian citizenship was cancelled. It says his status can be tested in court. Prakash is in jail in Turkey.

The PJCIS was already partway through a statutory inquiry into the existing citizenship law when the new legislation landed last week. It is now running a parallel inquiry examining the new bill.

The legislation includes a clause pushing out the first inquiry’s deadline to 2021 – meaning the changes would have become law before the report on the current law was completed.

After negotiation, both reports are now due on December 1. Parliament won’t vote on the bill until after that.