From the killing fields of Cambodia to the ongoing nightmare in Darfur, why has the world traditionally stood by as governments fail to protect their own people from genocide, ethnic cleansing, or other crimes against humanity? Gareth Evans explains why mass atrocities continue to go unchecked and how the emergence of new international norms, such as the Responsibility to Protect, can guard citizens from falling victim to mass crimes. A former Australian Foreign Minister and leading international advocate in conflict prevention and resolution, Evans co-chaired the international commission that initiated the Responsibility to Protect idea in 2001.