Background: Persons with schizophrenia have a small but significant increase in risk of violence, which remains after controlling for known environmental risk factors. In vivo MRI-studies may point toward the biological underpinnings of psychotic violence, and neuroimaging has increasingly been used in forensic and legal settings despite unclear relevance.Objectives: (1) To present the first systematic review, following standardized guidelines, of MRI studies of violence with schizophrenia. (2) To critically discuss the promises and pitfalls of using this literature to understand violence in schizophrenia in clinical, forensic, and legal settings.Methods: Following the PRISMA guidelines and literature searches until January 2018, we found 21 original studies that fulfilled the inclusion criteria: (1) Studies of persons with schizophrenia, (2) a history of violence or aggressive behavior, (3) the use of one or more MRI-modalities (sMRI, DTI, fMRI).Results: The most consistent findings from the structural studies were reduced volumes of the hippocampus and the frontal lobe (in particular the orbitofrontal and anterior cingulate cortex) in schizophrenia patients with a history of violence or higher aggression scores. The functional studies mainly showed differences and aggression correlates in the frontal lobe and amygdala. However, the studies were methodologically heterogeneous, with four particular areas of concern: different definitions of violence, region of interest vs. whole-brain studies, small subject samples, and group comparisons in a heterogeneous diagnostic category (schizophrenia).Conclusion: The literature reports subtle, but inconsistent group level differences in brain structure and function associated with violence and aggression with schizophrenia, in particular in areas involved in the formation of psychosis symptoms and affective regulation. Due to methodological challenges the results should be interpreted with caution. In order to come closer to the neurobiological underpinnings of violence in schizophrenia future studies could: (1) address the neurobiological differences of premeditated and reactive violence, (2) use RDoC criteria, for example, or other symptom-based systems to categorize psychosis patients, (3) increase subject cohorts and apply new data driven methods. In this perspective, MRI-studies of violence in schizophrenia have the potential to inform clinical violence prediction and legal evaluations in the future.

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How mental disorder relates to criminal insanity is a contested matter. Norway has a tradition of using a ‘medical model’ for the definition of criminal insanity that is unique in an international perspective. According to this model, insanity is determined only in relation to a medical criterion, so that all that is required is the presence of a qualifying mental disorder. Criminal insanity is, under the current rule, equated with psychosis, although this rule has recently been subject to a law reform. This article explains and discusses this medical model by gathering together legal, forensic, and clinical empirical perspectives on the legal meaning and relevance of psychosis. The article will provide an explanation of the background of the medical model in Norwegian law, and the justifications for tying criminal insanity to psychosis. It will also explain how criminal insanity is operationalised in forensic practice, and discuss the legal conceptualisation of psychosis from a medical perspective. A main conclusion is that the legal meaning of psychosis is unclear, and the authors describe several challenges in legal and forensic practice. The authors emphasise the need for further knowledge development in the intersection between law and medicine.