Montaigne Centre Blog


Legal Aspects of the EncroChat-Operation


In the EncroChat operation, French law enforcement authorities collected over 120 million messages from 60.000 EncroChat users. They cooperated with Dutch law enforcement authorities and Europol in a Joint Investigation Team (JIT). In the Netherlands, EncroChat data has already been used in over 200 criminal cases. In this blog, we explain how the right to a fair trial proved particularly important for defence attorneys. For example, with reference to the principle of the equality of arms, it aided in obtaining details about the way evidence was collected and processed in the EncroChat operation. This blog is a summary of our article about then EncroChat operation and presents our main findings.

Introduction and research question

In our article, ‘Legal Aspects of the EncroChat Operation: A Human Rights Perspective’, we examined what lessons can be learned from the Dutch experience with the EncroChat operation from a human rights perspective, in particular the right to a fair trial. The full article is published in open access in the European Journal of Crime, Criminal Law and Criminal Justice.

As compared to other legal systems, the Dutch judiciary published a large number of cases at First Instance Courts and Courts of Appeal, in which EncroChat evidence is used. Dutch courts extensively considered arguments of defence attorneys relating to the right to a trial. Therefore, it is interesting for lawyers from other legal systems to review the state of knowledge in the Netherlands.

In order to explain what lessons can be learned from the Dutch experience, we set out the known facts about the operation, show how Dutch courts dealt with legal questions arising from the operation and examined relevant case law of the European Court of Human Rights (ECtHR).

We conclude that the right to a fair trial in Article 6 ECHR proved important in Dutch case law in three ways:

  1. Providing transparency about the operation;
  2. Providing a legal basis to test the reliability of the evidence obtained; and
  3. Providing access to data used as evidence against suspects in a criminal case.

1. Transparency about the operation

In our article, we explain how unrelenting questions of defence attorneys, with a(n) often implicit) basis in article 6 ECHR, led to discovery of details about the EncroChat operation in France and how the data was shared by French authorities and further processed by Dutch authorities. That was no easy feat, as the French declared the operation a state secret and the Dutch judiciary accepted that as fact with regards of the principle of trust.

Keeping the operation secret challenges the right to a fair trial under article 6 ECHR, more specifically the principle of equality of arms. Part of the principle of equality of arms is transparency about the manner in which the evidence is gathered. Law enforcement authorities and the public prosecutor can have a legitimate interest to keep information about the operation secret. However, keeping this information secret is allowed only insofar as it is strictly necessary and must be counterbalanced by the procedures followed by the judicial authorities.

In the Netherlands, as a counterbalance, an extra warrant must be obtained to create a subset of the EncroChat data to use it in a (new) criminal investigation. This way another (Dutch) judge will test the principles of proportionality and subsidiarity with regard to the processing of the EncroChat data, while taking into account the reproducibility of evidence and the protection of privileged communication.

2. Testing the reliability of the evidence obtained

The right to a fair trial also provides a legal basis to test the reliability of the evidence and the method of acquisition. When software is used in the collection of data, this can have a major influence on the reliability of evidence, because it challenges the confidentiality, integrity and availability of data.

Dutch case law shows that the Netherlands Forensic Institute reported that the hacking and interception software did not operate continuously, not all messages on EncroChat phones were intercepted during the entire operation and there had been instances of a mix-up in outgoing and incoming calls from EncroChat phones.

However, these shortcomings did not lead to the conclusion that all evidence from the EncroChat operation is unreliable. So far, Dutch defence attorneys failed to establish that the EncroChat data used as evidence was unreliable and no data has been excluded from evidence.

3. Access to EncroChat data

The right to a fair trial enables the defence – to a certain extent – to access EncroChat data that may be relevant in the trial against their client. Suspects need to be able to access the data in order (a) to review its integrity; (b) to review its reliability (because all EncroChat messages are sent under pseudonyms); and (c) to determine whether exculpatory evidence can be found in the dataset.

Our analysis of case law of the ECtHR shows that, while suspects cannot access all information collected in the EncroChat operation, they have a right to access data that is deemed relevant in their case. In addition, the defence should be able to reason why they require further access to EncroChat data, including data that is not part of the dataset created by the public prosecution service. They should also have the sufficient facilities (an ‘effective opportunity’) to access and analyse the data.

In the Netherlands, the defence can argue why they should be able to access both types of data based on key words and the use of filters. Sometimes access is refused because of ongoing (other) criminal investigations or for privacy reasons of individuals involved. The defence is facilitated in accessing the data at the Netherlands Forensic Institute and can use the same software as law enforcement authorities use to search and analyse the EncroChat data themselves. They can also request the data, which could then be provided to the defence in a readable format.


In conclusion, legal practitioners can learn from the Dutch experience with criminal cases following from the EncroChat operation. Especially arguments of defence attorneys relating to the right to a fair trial and the way Dutch practice dealt with these questions are noteworthy.

The following three lessons can be learned:

  1. Defence attorneys will demand more transparency about the way the evidence is collected following the EncroChat operation. Some details about the operation may be kept secret, but must be counterbalanced. In the Netherlands, additional warrants with specific safeguards must be obtained to create a subset of the collected data. This data can then be used in a new criminal investigation. We argue this should be viewed a good practice.
  2. Defence attorneys will question the reliability of the evidence. The public prosecution service and law enforcement authorities should prepare for this argument and explain why the particular EncroChat data that is used in a criminal investigation is reliable. In addition, we recommend that other sources of evidence are used besides EncroChat data. Multiple sources of evidence may validate each other and strengthen the case.
  3. The defence has a right to access data that is used as evidence against a suspect. In the Netherlands, the defence now has the practical means to access this data and the right to argue why they should have access to a larger dataset. The defence is also facilitated in accessing the data in readable format. In our view, the public prosecution office and judiciary should prepare for requests of defence attorneys to access EncroChat data and States should invest in an infrastructure to facilitate these requests.