Must an outgoing commander prevent his troops from criminal activity even if their crimes will be committed after he ceased to have effective control over them? This question has received scant judicial or academic attention. Yet, the question is not simply hypothetical. In the Sesay et al. trial judgment, the accused Morris Kallon incurred command responsibility for his failure to prevent enslavement, which continued until December 1998, even though his effective control over the culpable troops ended in August 1998. While the trial chamber provided little reasoning for its conclusion, this paper endeavours to fill that gap in research and discussion by explaining 1) that all the elements of command responsibility under customary international law can be met at the same time, without contemporaneity with the subordinate’s crime; 2) that command responsibility beyond a commander’s period of effective control is consistent with a principled reading of the doctrine of command responsibility which seeks broad compliance with international humanitarian law to prevent violations thereof; and 3) why actual and theoretical arguments against the advocated position, such as those levelled by the majority in the 2003 Hadžihasanoviü Interlocutory Appeal, do not withstand scrutiny. This paper concludes that the customary law principle of command responsibility obliges a commander to prevent his subordinates from committing crimes at all times when he has the requisite knowledge and material ability to do so, regardless of whether the crimes were eventually committed after the commander left his position of command.