When criminal liability is imposed on a person, the judgment must state how the person's culpability in terms of intent or negligence was established. If the defendant was suffering from a serious mental disorder at the time of the crime, the court has often had to make difficult legal decisions, partly based on expert medical reports. If the defendant was also young, especially at the age of 15, the personal development and experience of the young person may make it even more complicated for the court to assess liability. This problem is partly due to the fact that under Swedish law, criminal liability can be imposed even if the defendant was suffering from a serious mental disorder at the time of the offense. However, intent or negligence on the part of the defendant must always be proven. The project aims to collect and systematize case law regarding how the courts reason when determining criminal liability in cases where the defendant suffered from a serious mental disorder at the time of the offence and was aged 15-21 years. Since these persons are a particularly vulnerable group, the requirement of a fair trial under Article 6 ECHR also gives reason to examine these cases more closely.