Universiteit Leiden

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‘Justice is not possible without determining the truth’

Professor of Criminalistics Charles Berger thinks miscarriages of justice can be avoided more often by clearer determination of the truth. He therefore not only wants to focus on the advancement of forensic science, but also on improving lawyers’ reasoning of the evidence. Inaugural address on 3 February.

To allow as few guilty individuals as possible to go unpunished. That is one of the key objectives of the Dutch legal system. However, the reverse then certainly must be equally important: punish as few innocent individuals as possible. According to Berger, the only way to move forward with both these objectives is by improving the determination of truth.


‘Too often in these cases, something goes amiss in the interpretation of evidence, including trace evidence, eye witness testimony or the alibi of the accused,’ Charles Berger states. On 3 February, he will accept his re-appointment as professor by special appointment of the chair in Criminalistics, funded by the Netherlands Forensic Institute. ‘Forensics science is becoming continually more advanced; however, for progress on the ground to be effective, lawyers themselves must gain greater knowledge of the scientific principles of determining truth.’

Basic principles

In his inaugural lecture, Berger shows how investigators and lawyers can reach a fully informed, rational judgment. For example, they can avoid tunnel vision by considering several hypotheses, including those in the investigative phase, in which the defence is still deciding how best to defend the interests of a suspect. Was the suspect the person who strangled the victim, or did his DNA arrive at the scene of the crime in some other way? By working with such hypotheses, forensic investigation can much more effectively contribute to determining the truth in the case.

Contextual bias and objectivity

Professor Berger argues that in criminal investigations, bias informed by contextual information must be avoided whenever possible. ‘It is better if a forensic investigator does not know whether a suspect has confessed. Such a confession clearly influences the probability of the hypotheses, but has no bearing on the evidential value of the material investigated. ‘To avoid undue influence, an initial expert can study a case file, and then only pass on the information that is relevant to the task of a second expert. In addition, much progress has been made in terms of objectivity given that signatures, fingerprints and flammable agents can be compared increasingly better automatically.

Activity is a key issue

‘Much forensic investigation focuses on the question of who or what left a particular trace. That's rather strange, because leaving a trace is not punishable. In practice, the key question is usually whether the defendant has performed a particular criminal act or not.’ Because this so-called activity question is much more relevant to the case than questions about the source of a trace, in Berger’s opinion, this will pose a major challenge for forensic research in the coming years.

Knowledge transfer

Berger believes that in recent years, scientific progress has been made in all these areas, and this progress must now be reflected in the knowledge the users of these expert reports have. ‘I have put a lot of energy into the transfer of knowledge to police and lawyers in recent years. They must be enabled to gain greater knowledge to make optimum use of forensic reports. This is where universities can play an important role. It’s remarkable that practising lawyers are currently receiving more education on determining the truth than lawyers in training.’