Law threatens punishment from civil or institutional bodies. For Religion, right and wrong are defined by authoritative scripture or revelation. Eternal reward or punishment is often perceived as being involved. For Custom, the notions of appropriate and inappropriate are central. Tradition provides the basis for determining what's appropriate.
Punishment comes in the form of social approval or social condemnation.
The discipline of Anthropology has had a major impact, this century, on the way we think about society. It has led to the view called Cultural Relativism. This is the view that societies differ profoundly in regards to the values supported, the ends pursued, and the meanings that are attached to various activities. This view has transformed earlier assumptions regarding the relative sophistication of certain societies, particularly Western societies, as compared with others. In addition, it is a view that has been regarded as so influential that it is often perceived as providing strong evidence for the validity of Ethical Relativism.