Emeritus professor of Legal Psychology at Vrije Universiteit Amsterdam Peter van Koppen has been called upon as an expert witness in many major criminal cases. He was, for example, involved in the cases of the Arnhemse villamoord, the Bredase restaurantmoord and the Schiedammer parkmoord. After a fascinating career, he was named Officer in the Order of Orange-Nassau because of his highly relevant international contributions to the field of legal psychology. His education, work and the field of legal psychology will be discussed in this interview.
Van Koppen earned his doctoral degree at the Erasmus University Rotterdam in 1984. Additionally, he worked at Erasmus School of Law from 1978 until 1992. Among other things, Van Koppen gave lectures on civil and criminal law. But his passion remained with legal psychology, discussing real cases with students and conducting (international) research.
You studied Psychology first and then started with Law. Why this combination?
“Because I did not like either of them”, Van Koppen laughs. “No, I grew up in a catholic home, so I went to an all-boys school. My big love was, and still is, architecture. Because then you actually make something. What we are doing is mostly words, words, words”, Van Koppen says. “Then I went to an open day with my mother in Delft; Engineering. And there were also only boys.” Van Koppen wanted a change of scenery. “After tough negotiations with my father, I was allowed to go to Groningen because it was the university furthest away from Haarlem.” Van Koppen has always had a good relationship with his parents. Nevertheless, he chose to go to Groningen: “I wanted to spread my wings. I had just turned seventeen”.
Van Koppen’s father hugely influenced the study choice of his son. “My father allowed me to choose between Law and Economy. So, I picked Economy”, he continues. “That lasted two weeks. It was too complicated”, Van Koppen laughs. “Then I started with Psychology, which I kept a secret from my father for half a year.”
“My father was a lawyer. So I grew up with law at the breakfast table. I have always found it to be fascinating. One day I decided to study Law as well”, the emeritus explains. Van Koppen completed his first year in Groningen but continued his law degree in Amsterdam upon recommendation from his cousin. “I obtained my bachelor’s degree there”.
“Then I started studying in Rotterdam. However, I quit just before the last exam. Otherwise, my father wanted me to become a lawyer”, Van Koppen says. “And I really did not want that”. Nevertheless, he obtained his PhD in Law at Erasmus School of Law.
What did you like most during your study time?
“Going crazy”, Van Koppen answers straight away. “Your student days are the ideal time to explore yourself and the world. I spent a lot of time acting, and I partied. Meanwhile, you learn a craft. But the most important thing was discovering yourself and the world”.
Van Koppen describes a few lectures that he enjoyed massively. He compares his student days with those of current students. “We had an outstanding philosopher at the Psychology faculty. And his lectures were always packed. Students from various faculties visited these lectures, even though they did not get any credits for them. Because you just studied. The exams were, sometimes, a slightly annoying, side issue. Nowadays, students are too driven, too serious, and way too interested in the exam details and less interested in what they are actually learning.”
What is legal psychology?
“It is the psychological side of the law”, Van Koppen explains. According to the emeritus, legal psychology can be divided into two parts: “The first part is the functioning of the law. This part deals with easy questions like: do we influence people’s behaviour by making certain laws and regulations?” The other side of legal psychology focuses on the participants of the legal system. Van Koppen gives a few examples: “Witnesses, statements of suspects, the behaviour of police, decisions of judges and prosecutors and negotiation behaviour of lawyers.”
What did your work as a legal psychologist entail?
Van Koppen gave lectures and conducted research. Additionally, he was often called upon as an expert witness. “And that results in many interesting cases, which you can also use for lectures. An advantage is that I knew all the ins and outs of these cases. So, I knew what I was talking about.”
Moreover, Van Koppen established the project ‘Gerede Twijfel’ [red. loosely translated: Reasonable Doubt]. This project is connected to the Vrije Universiteit Amsterdam. “It started as a coincidence”, Van Koppen states. When the case of the Schiedammer parkmoord was dealt with in the court of appeal, various experts that doubted the guiltiness of the suspect – including Van Koppen – came together. “One argued that I had to write a letter to the court of appeal; stating that they were going to convict the wrong person.” However, Van Koppen instead wanted to analyse the case properly with a group of students. After receiving the complete file, he set out to do exactly that. Unfortunately, the publication of this analysis did not cause the desired change. “What you do see since this case and the Puttense moordzaak is realising that it can go wrong”, Van Koppen states. “Before those cases, that realisation was not there. The second thing that I have seen is that one started thinking in scenarios. That is crucial”.
Is this also the case that stuck with you?
Van Koppen explains that this was not the case. Many cases have not stuck with him, but he can still recall others in every detail. “And that is because either the story is different, or the story is horrible”, he states. “One of the most horrible cases I have ever worked on involved a, to my opinion, relative insane couple that looked after a boy for a man who was a truck driver and whose wife joined him for a week. That pair practically tortured that boy to death and subsequently threw him from their balcony. Dead. And in their statements, they said: “We behaved just like his mother did”. Therefore, people were not very interested in this couple but focused mainly on the mother, who was pregnant again. She was in custody, but the prosecution’s goal was to make sure that she would not be allowed to keep her own child. That is a case that shakes me to my core if I read the files. That can keep me up at night.”
What does the project Gerede Twijfel consist of?
After investigating the Schiedammer parkmoord, Van Koppen continued the project Gerede Twijfel. “We try to look at two cases a year”, states the emeritus. For every case, a new group of students is composed. Students of all faculties and all universities can apply for this. The cases are also subject to a selection procedure. “The cases have to be interesting for students; they have to be able to conduct some sort of research”, Van Koppen explains. Therefore, the cases often involve murder.
Van Koppen describes the example of the dancing perpetrator: “A woman was beaten to death, and all the bushes surrounding the murder scene were covered in blood. So, the perpetrator must have been covered in blood as well. The suspect’s clothes were put in the laundry machine, which had completed half a program. And not a drop of blood was found. Also, not on his shoes, which were – obviously – not put in the laundry machine. We imitated this; can you put clothes covered in blood in the laundry machine without finding any of it? Of course, we did a reliable preliminary measurement to check whether there was blood in the laundry machine, the disposal or chiffon. Subsequently, we picked up a bucket full of blood at the slaughterhouse, and we splashed it on the clothes. Then we washed them with the same laundry detergents the suspect had used. And what did we find? A lot of blood.”
Will similar projects appear in the rest of the Netherlands?
“No”, Van Koppen states. “It is, in many ways, an unprofitable project”. “There is no law faculty that shows you real cases, at least not this type of complex ones. Sometimes, you get small practice cases. And that has a function. Because the messy, real world differs from the everyday situations that are taught”.
What did you enjoy the most within legal psychology?
Van Koppen explains that he enjoyed the project Gerede Twijfel the most. He will continue with this now he is retired. “If you give a lecture, you tell a story”, he states. “But with Gerede Twijfel, you look at a real case. It is real-life education.” Together with students, Van Koppen must constantly face new facts. Van Koppen: “It is more of a quest with the students; How do we solve this problem? How can we establish what has happened at this point?”
What should be the next step to purify decisions within criminal cases?
“Take the facts more serious”, Van Koppen answers straight away. “In my opinion, judges convict too often based on evidence that does not make any sense.” He stresses that it is vital to often take a step back. “Look at the alternative; does your evidence distinguish between the prosecution’s scenario and the alternative scenario? And one does not often do so. Evidence frequently fits the prosecution’s scenario, but also other scenarios.”
“Take this glass, for example”, Van Koppen says while pointing at a glass in front of him. “Does it contain water? Why do you think it does? It is a question that one can be investigate; you can smell it or taste it. But when you decide the glass contains water, and you often do so without tasting it, you also decide that there is nothing else in it: no vodka, no gin, no coffee. Many people then assume that there is water in the glass without giving it a second glance. Most of the time, it is not that complicated. Many suspects that appear in front of a judge are guilty. The only interesting question that remains is what the punishment should be. Therefore, the routine is: we know how it is composed, and the pattern is correct. In more complex cases, one applies the same routine too often.
Van Koppen stresses that it is essential always to think a few steps ahead. “Never assume anything without actively verifying its truth. That was emphasised during my days as a psychology student. However, it is also crucial within the field of law. Ask yourself the question: Is it correct what I am assuming?”