A number of case histories have reported an association between the presence of misidentification syndromes and violent behavior. If patients with such delusions are truly more likely to perpetrate violent acts, treating mental health professionals could potentially be considered liable for not warning or protecting potential victims. However, the purported association between violence and misidentification can be adequately explained by biased case ascertainment and reporting. The current literature on misidentification syndromes is used as a means of demonstrating possible sources of error and bias that must be considered whenever mental health professionals are asked to reach conclusions about the relationship of rare events.