International law distributes power, resources, and rights to individuals, states, corporations, and other entities. International courts adjudicate key ethical questions such as the expression of religion in public, the rights of groups, or the duty to prosecute or to amnesty heinous violations. States use international law as a justification both for military intervention and for the refusal to intervene. Refugees fleeing war zones encounter international law when they cross borders, enter camps, plead for citizenship, search for food and water, or claim basic rights. Whether considering the international order from the perspective of the most or the least powerful people or groups, comprehending it requires understanding the power, limit...