The number of non-state actors, traditionally not accountable for committing war crimes or violating human rights, is proliferating exponentially. As criminal gangs, individuals in weak states organizing to protect their local communities, armed groups operating transnationally, and rarely analysed cyber organizations now account for the vast majority of today's armed conflicts, a new and increasingly important question has to be raised as to whether, and at what point, culpability arises under international law, and at what level of organization groups become accountable. Breaking new ground in addressing international human rights, international criminal law, and international humanitarian law in one swoop, Rodenhauser's text will be essential to academics and practitioners alike.