As humans, our perceptions and judgments are naturally colored by our beliefs, experiences, and desires. Consequently, two individuals with different mindsets or working in different contexts may interpret the same information in markedly different ways (i.e., cognitive bias), especially when that information is ambiguous. In forensic and medicolegal settings, cognitive bias can influence expert decision-making in ways that produce costly miscarriages of justice. In this chapter, we first review the sources of cognitive bias, including irrelevant contextual information, base rate expectations, stress, and allegiance. Then, we review research showing that cognitive bias can affect medical diagnoses of living individuals as well as postmortem manner-of-death judgments, and we discuss the reactions—both positive and negative—to these findings. Lastly, we describe best practices for mitigating the impact of cognitive bias and maximizing the value of medicolegal judgments.