From a long, but interesting scholarly paper by Kopel et al:

…civilian armament has historically been very effective at preventing genocide. Indeed, genocide scholars have found that genocides are carried out almost exclusively against populations which have first been systematically disarmed. Because genocidal regimes consider prior disarmament the sine qua non for beginning a genocide, it seems indisputable that civilian armament deters genocide in most cases. Part IV considers the practical possibilities of arming the Darfur genocide victims…

…we carefully analyze the international law implications of arming genocide victims. Genocide victims who acquired arms, and persons who supplied arms to genocide victims, would almost certainly be in violation of the gun control laws in the country where the genocide was taking place. In addition, the arms acquisition might violate international treaties against bringing arms into a nation without the consent of the national government. Under international law, could the genocide victims and their arms suppliers claim that their actions were nevertheless legal? We answer