Use of assessment instruments in forensic evaluations of criminal responsibility in Norway

Objectives Assessment instruments are often used to enhance quality and objectivity in therapeutic and legal settings. We aimed to explore the use of instruments in Norwegian reports of forensic evaluations of criminal responsibility; specifically, whether this use was associated with diagnostic and forensic conclusions. Methods Our study has an exploratory cross-sectional design. We examined 500 reports filed with the Norwegian Board of Forensic Medicine in 2009–2018 regarding defendants indicted for the most serious violent crimes. The first author coded data from all reports according to a registration form developed for this study. Two co-authors then coded a random sample of 50 reports, and inter-rater reliability measures were calculated. The first author coded 41 reports for calculation of intra-rater reliability. Descriptive statistics are presented for the use of assessment instruments, and a generalized linear mixed model (GLMM) was used to estimate associations between the use of instruments and diagnostic and forensic conclusions. Results Instruments were used in 50.0% of reports. The Wechler’s Adult Intelligence Scale (WAIS), Historical Clinical Risk-20 (HCR-20), and the Structured Clinical Interview for DSM disorders (SCID I), were used in 15.8, 13.8, and 9.0% of reports, respectively. The use of instruments increased from 36% in 2009 to 58% in 2015; then decreased to 49% in 2018. Teams of two experts wrote 98.0% of reports, and 43.4% of these teams comprised two psychiatrists. In 20.0% of reports, the diagnostic conclusion was schizophrenia, and in 8.8% it was other psychotic disorders. A conclusion of criminal irresponsibility was given in 25.8% of reports. Instruments were more often used in reports written by teams that comprised both a psychiatrist and a psychologist, compared to reports by two psychiatrists. The use of instruments was strongly associated with both diagnostic and forensic conclusions. Conclusion Instruments were used in 50% of reports on forensic evaluations of criminal responsibility in Norway, and their use increased during the study period. Use of instruments was associated with diagnostic and forensic conclusions.