"Difficult to question the evidence because you do not have access to everything"

Swedish police have previously used the Encrochat app to arrest criminals.

In one of the cases, however, the Court of Appeal has chosen to acquit a person.

- It was not possible to prove according to the Court of Appeal that it was this person who had used the mobile phone.

The defense had also not had the opportunity to question and take part in the evidence, says Dennis Martinsson, PhD in criminal law at Stockholm University.

Hear more in the clip above.