Genetic information is increasingly used in many contexts, including health, insurance, policing and sentencing-with numerous potential benefits and risks. Protecting from the related risks requires updates to laws and procedures by justice systems. These updates depend to a large extent on what the key stakeholders-the judiciary-know and think about the use of genetic information. This study used a battery of 25 genetic knowledge items to collect data from 73 supreme court judges from the same country (Romania) on their knowledge of genetic information. Their responses were compared with those of two other groups: lawyers (but not judges; N = 94) and non-lawyers (N = 116) from the same country. The data were collected at approximately the same time from the three groups. The judges' results were also compared to the results obtained from a general population data collection (N = 5310). The results showed that: (1) judges had overall better knowledge of genetics than the other groups, but their knowledge was uneven across different genetic concepts; (2) judges were overall more confident in their knowledge than the other two groups, but their confidence was quite low; and (3) the correlation between knowledge and confidence was moderate for judges, weak for lawyers and not significant for non-lawyers. Finally, 100% of the judges agreed that information on gene-environment processes should be included in judges' training. Increasing genetic expertise of the justice stakeholders is an important step towards achieving adequate legal protection against genetic data misuse.