Justice is simultaneously a practical and an ideal concept: when we think of justice, we refer to its day-to-day administration, involving police, lawyers, judges, and politicians--but we also refer to a larger ideal, a set of basic values that guide our attempts to live together and balance competing interests, obligations, and freedoms. If we lose sight of the practical, the ideal will fail--but if we forget the ideal, the practical becomes pointless.<br> <br> <br> <br> <i>On Rules</i> is the culmination of decades of thinking about and working within the law as both an ideal and a realm of