The legal fallout from Islamic State’s short but bloody existence is both complex and enduring. For those Westerners who travelled to Syria and Iraq to join the jihadist project, which ended with the fall of Baghouz in southeastern Syria in March 2019, justice has taken different forms. Many were killed by Syrian or Iraqi government forces, in air strikes carried out by their own country or that of an ally, or by armed groups supported by the West. Those men and women that survived the five years of conflict have been variously detained, tried in foreign jurisdictions, had their citizenship stripped and been left to languish in identity limbo, or been deported and tried at home.

What path justice has taken has depended on their individual circumstances and their country’s policies and legal procedures. France, for example, has been happy for its nationals to face local justice, whereas the United States has largely sought to repatriate and try its citizens in American courts. Turkey, for its part, has become increasingly willing to deport foreign fighters rather than deal with them through the local court system.

This all begs the question about whether Westerners who travelled to Syria to join Islamic State or other jihadist groups are better off being subject to court processes at home or in a foreign jurisdiction.

The short answer is that it depends.

Without doubt, the least hospitable jurisdiction for Islamic State members from Western countries is Iraq. 

In the West, there are remarkable similarities in the average sentence for convicted terrorist offenders. A Lowy Institute analysis of people charged with terrorist offences in Australia during the Islamic State era has shown that the average sentence for the 59 convicted to date is 13.7 years. This is remarkably similar to the experience in the United States, where a similar study shows the average sentence for the American cohort is 13.2 years. And in Canada, the average sentence for all types of terrorism offences has been 13 years.

Punishment in European courts for radical Islamist terrorism offences has been historically lighter, but has taken on a harsher tone as more cases have been heard. The average sentence has risen in recent years from five to nine years imprisonment.

But in Turkey and Iraq, the two jurisdictions that have dealt with the largest number of Islamic State adherents, there are significant disparities in the approach taken to Western foreign fighters in their judicial systems.

There has been criticism of Turkey’s attitude to the large numbers of Islamic State foreign fighters passing through its courts. Relatively light sentences have been handed out and overly generous discounts given for displays of remorse, where the sincerity of such remorse is open to question. There are no figures for the total number of Westerners tried for Islamist terrorism offences in Turkey, but we do know of at least five British and Australian nationals who have faced Turkish criminal courts. Taking into account their appeals and reductions in sentences for cooperation or personal circumstances, the average sentence amounts to less than five years.

Among these was the British national Aine Lesley Davis, who received the lengthiest prison sentence of seven and a half years – he is believed to have been a member of the group of four British Islamic State members dubbed “The Beatles” who were involved in the kidnapping and deaths of several Westerners in Syria. Two other members of that group have recently pleaded guilty in the United States and will receive life sentences.

Without doubt, the least hospitable jurisdiction for Islamic State members from Western countries is Iraq. A number of Westerners captured in Syria were subsequently transferred to Iraq and put on trial, with the proceedings swift and the sentences harsh.

In 2019, an Iraqi judge passed death sentences on 11 French nationals for being members of Islamic State. Three other French citizens, including two women, were handed life sentences, and a German woman had her death sentence commuted to life imprisonment the same year. Australian Ahmed Merhi and his Lebanese cousin Tarek Khayat were also sentenced to death in late 2018.

Given the vagaries of national legal systems and the difficulties Western countries face in terms of gathering evidence that is admissible in court, there can be no standardised legal approach to dealing with Islamic State militants. However, between the apparent harshness of the Iraqi legal system and the relatively light sentences handed out in Turkish courts, the legal systems in the West appear to have adopted an approach to their cohorts of Islamic State foreign fighters that is both relatively consistent and relatively robust.

As a result it strengthens the argument of those who advocate for all Western countries to try Islamic State foreign fighters in their home jurisdictions.