One of the principal purposes of the Rome Statute is the prevention of future international crimes. To achieve this goal, the International Criminal Court (ICC) must consider the effects that its law enforcement measures will have on the commission of atrocities in a situation under review. This article responds to the need for context-specific empirical research elucidating the effects of ICC interventions. Reviewing evidence from the situations subject to ICC intervention over the past two decades and advances in social psychology and neuroscience, this article offers a number of factors the ICC should take into account when deciding whether to pursue an investigation or prosecution. First, when conducting the positive complementarity analysis and determining whether an investigation or prosecution would not
serve the interests of justice, the ICC should consider whether deferring a prosecution would prevent international crimes. The situation of Colombia provides a prime example of a case in which the ICC should defer to the domestic jurisdiction, because the deferral promoted both accountability for international crimes and the prevention of future atrocities. In deciding whether an ICC investigation or prosecution would not serve the interests of justice, the ICC should also take into account the stage of a conflict, the relative power of the targets of the ICC’s actions, and the presence of psychological factors in the situation, including dehumanization, an overpowering authority, posttraumatic stress disorder, and the use of drugs and child soldiers. Only by adopting such nuanced approaches to international prosecutions will the ICC be able to accurately predict the effects its actions will have in a situation and promote the purposes of the Rome Statute.