Interview with Petra de Jong and Arjen Leerkes | WODC Researchers published in by Wilmer Heck published on Newspaper NRC
From registration in police systems, to referral to the Public Prosecutor’s Office (OM), to the judge’s decision and the imposition of detention: people with a migration background become increasingly overrepresented at each stage of the criminal justice process. How can that be?
While people with a migration background make up a minority of arrests in police statistics, they end up being the majority of those sentenced to prison. How is that possible? This question arose in 2021 when Minister Ferd Grapperhaus (Justice and Security, CDA) sent a newsworthy scientific insight to the House of Representatives: proportionally more people with a migration background are in prison than police data would suggest. Grapperhaus was responding to a motion from SGP MP Kees van der Staaij, who raised concerns about the “worrying overrepresentation” of people with a migration background in crime statistics.
The minister’s initial answers were positive. Across all ‘origin groups,’ crime had “declined sharply” over the past fifteen years. People with a migration background were indeed overrepresented, but for most groups, this could be explained by factors such as younger average age — when crime is more prevalent — as well as lower average education levels and income.
Still, among people with Antillean, Aruban, or Moroccan backgrounds, “a certain degree of overrepresentation” remained even after correcting for these factors. The scientific debate on why this occurs is ongoing.
But why does the share of people with a migration background increase at every step in the justice chain — from arrest to sentencing? Grapperhaus tasked the WODC (Research and Documentation Centre) to investigate, and researchers Petra de Jong and Arjen Leerkes have now published initial findings.
How exactly do you see the overrepresentation of people with a migration background increasing at each step in the justice process?
De Jong: “Among minors, 46% of suspects registered by the police have a migration background. Among those minors referred by police for prosecution, that increases to 49%. Of the cases brought before a judge, that’s 56%. And when it comes to detention being imposed, the share of convicted minors with a migration background rises to 67%.
Among adults, the share increases from 45% of suspects to 55% of those who receive detention.”
Why does this happen?
De Jong: “Part of the difference can be explained by the type of offense committed. On average, people with a migration background are more often involved in offenses that carry a higher likelihood of prosecution and detention. We can also attribute some of the increasing share to group differences in the number of suspicions. On average, there are more suspicions against people with a migration background, which more often leads to detention.”
Leerkes: “Group differences in background characteristics also play a role, such as education level. We can’t test why that is in this study, but it’s possible that higher-educated people are assessed as posing a lower risk of reoffending, making them less likely to end up in court or receive detention. It could also be that they behave in a manner more aligned with what the court views as appropriate.
Even when we control for all these factors, there still remains a substantial part of the migration-background-related difference unexplained — particularly in the steps where the prosecution refers someone to court and where the judge imposes detention.”
De Jong: “We interpret this as an indication of direct ethnic selectivity — meaning selection based more closely on the ethnic background of the suspect. This could suggest negative sentiment toward groups with a migration background among judges, prosecutors, and other professionals in the criminal justice chain, though other causes may also exist. For example, statistics or perceptions about certain ethnic groups being more involved in specific crimes may influence judgments.
In previous research, judges also cited poor language skills or lack of a fixed address as reasons to impose detention rather than community service. Differences in courtroom behavior may also play a role — for example, willingness to confess. Youth from authoritarian households may be less inclined to confess out of fear of the consequences at home.”
Where do you see the greatest degree of ethnic selectivity in the criminal justice process?
Leerkes: “After adjusting for the type of offense, Dutch-born youth with at least one migrant parent are 28% more likely to receive detention than youth without a migration background. In the full model — where we also control for background characteristics and criminal history — the likelihood is still 22% higher.”
What is the main takeaway from this research?
Leerkes: “That people with a migration background face disadvantages at nearly every stage of the criminal justice chain. Among adults, we see that differences in the first step — the likelihood of being referred for prosecution — can be explained by the nature of the offense. So in that step, there doesn’t seem to be direct disadvantage.
But we also see unequal outcomes for comparable suspicions of criminal behavior. Part of that is due to the generally less favorable socioeconomic position of suspects with a migration background. Yet even after accounting for this, there remains a gap we cannot explain. We are now conducting further research into underlying mechanisms. These could include ethnic biases or stereotypes among staff, but also issues like poorer Dutch language skills among people with a migration background.”
“Dutch-born youth with at least one migrant parent are 28% more likely to receive a prison sentence than youth without a migration background.”
— Arjen Leerkes, WODC researcher
To what extent does this make our system discriminatory?
Leerkes: “I wouldn’t say we have a discriminatory system per se. We see social inequalities arise and become amplified within the justice chain, and different forms of discrimination likely play a part in that. But it’s difficult to determine exactly how much and to objectively define at what point the level of discrimination warrants labeling the system itself as discriminatory. So I would say: discrimination certainly occurs within the system — but that doesn’t necessarily make the entire system discriminatory.”
De Jong: “The judiciary is based on the principle of equal treatment and equal outcomes in similar cases. These findings raise questions about that. In individual cases, judges probably weigh the consequences of a sentence with good intentions, taking into account things like whether the person has a job, housing, or a partner — which may be considered mitigating factors.
However, poor command of Dutch may result in a case progressing further down the chain, and increase the likelihood of detention. Our research suggests that, at an aggregate level, this can lead to systematic inequalities — where groups with a less favorable socioeconomic position, such as those with a migration background, are disadvantaged in the justice system. This could deepen existing inequalities in society.”
What can be done about this?
Leerkes: “More than just the usual ‘bias training’ to combat unconscious prejudice. We also need to carefully examine certain procedural rules — for example, that admitting guilt can reduce the likelihood of detention. We’re conducting follow-up research into what else can be improved. But it’s essential that we have more discussions about how to structure criminal law in a diverse and socioeconomically unequal society.”