In the days before he declared he would challenge for the leadership of the Liberal Party, Minister for Home Affairs Peter Dutton announced he had revoked the Australian citizenship of another five dual nationals who had fought with Islamic State in the Middle East. Until then, only one other dual national had his citizenship revoked for his activities in Iraq. That person was renowned war criminal Khaled Sharrouf.

The Department of Home Affairs has not revealed the identity of those whose citizenship has been revoked, but we know they are mix of men and women who have fought with Islamic State in Iraq. At the time of the announcement, the Minister said the decision was made to prevent the return of foreign fighters as a means to keep Australians safe.

Allowing people who were born and raised in Australia to roam the globe after they’ve participated in Islamic State atrocities does little to contain the threat.

However, foreign fighters still have immense capacity to do harm to Australia and its national interests even if they never return. Australia remains obliged to hold them criminally responsible for their crimes under international law.

In 2016, Australia co-sponsored a UN General Assembly resolution establishing an accountability mechanism for the most serious crimes under international law committed in Syria. But the establishment of that mechanism was designed to support national judicial process. In his initial report, the Secretary General reminded the General Assembly that the primary burden rests with states to investigate and prosecute violations of international criminal law and to ensure full redress for these crimes as well as guarantee non-recurrence.

Revoking the citizenship of dual nationals who fight with Islamic State contravenes our obligation to prosecute and contradicts the guarantee of non-recurrence.

Islamic State and its affiliate groups are an increasing threat in our region. The organisation is responsible for abducting and holding hostage dozens of sailors and tourists in Malaysia, Indonesia, and the Philippines. The US Army counted a range of foreign fighters among the dead in the fight for Marawi in the Philippines. The second-largest number of foreign fighters arrested in Turkey comes from Indonesia, which has called for a regional response to returning fighters.

In March, ASEAN signed a Memorandum of Understanding with Australia to cooperate on countering international terrorism. The MoU included initiatives to combat the threat of Islamic-State-affiliated groups as well as issues relating to foreign fighters. Furthermore, “ISIS affiliates in Southeast Asia are effectively exploiting the cyber domain.” While much of this effort is for radicalisation and recruitment, Hararo Ingram has told us that the propaganda machine will continue to be deployed in “an epic battle for survival and relevance.”

Allowing people who were born and raised in Australia to roam the globe after they’ve participated in Islamic State atrocities does little to contain the threat.

In his announcement, Peter Dutton said the citizenship revocations happened automatically. But the Australian Citizenship Amendment (Allegiance to Australia) Act 2015 is unclear in its description of the process.

Section 35 of the Act alludes to the fact that a person automatically ceases to be a citizen of Australia at the time they commence fighting with armed forces of an enemy country or a declared terrorist organisation. But administratively, this seems unreasonable. Later, the Act speaks of the determination of revocation of citizenship.

Prior to the creation of the Department of Home Affairs, an advisory board of senior officials from a range of government agencies advised the Minister on individual cases. It is unclear if this process still exists under the new machinery of government, or if determinations are made solely within the Department of Home Affairs.

Either way, we know members of Islamic State are responsible for war crimes, crimes against humanity and genocide, including through the widespread use of sexual and gender-based violence. The Australian parliament has called for the investigation and prosecution of these crimes within our own courts. As signatory to the Rome Statute of the International Criminal Court, Australia is obliged to investigate and prosecute. We have national legislation criminalising these offences, but that legislation is not being used.

Institutional efforts being allocated to the identification of actions and the revocation of citizenship should be redirected for the purposes of criminal accountability.

In taking deliberate steps that actively inhibit criminal justice accountability, the government may even be opening itself to civil proceedings. Living victims of fighters who were dual Australian nationals may be able to sue the government for breeching its obligations. For example, we know Khaled Sharrouf was responsible for the purchase, enslavement and rape of several Yazidi women. In so doing, he perpetrated sexual violence as war crimes, crimes against humanity and genocide. His victims positively identified him as their captor, and publicly described what he did to them.

Rather than open a criminal investigation and attempt to prosecute him, the Australian government revoked Khaled Sharrouf's citizenship, leaving him solely a citizen of Lebanon, a country with no laws criminalising these acts and with no ability to prosecute him.