Complicity is a criminal law doctrine that attributes responsibility to those who do not physically perpetrate the crime. It is an essential mode of liability for core international crimes because it reaches out to senior political and military leadership. These persons do not usually engage in direct offending, yet in the context of mass atrocities they are often more culpable than foot soldiers. The Statutes of the ad hoc tribunals, hybrid courts and the International Criminal Court expressly provide for different forms of complicity, and domestic legal systems recognize it in one form or another. This is in contrast with alternative modes of liability implied from the Statutes to address the situations with multiple accused removed from the scene of the crime / (in)direct co-perpetration, extended perpetration and the joint criminal enterprise.