Is it possible to legally define religion?

Many legal systems reserve a privileged treatment to religious beliefs and religious groups, but they don’t provide for a legal definition of these concepts. This lack of legal definitions lead legal authorities to rely upon an implicit notion of religion, which is modelled by the historically and socially prevailing religious traditions. However, today’s transformations of the religious phenomenon make this implicit notion controversial and inadequate. The article examine the various attempts in defining religion provided up to now by legal scholars and judges, and try to identify a set of objective and explicit criteria useful to distinguish what is religious from what is not.