The history of law is many things. But one of them is the story of an unremitting struggle between rules and discretion. The tension between these two approaches to legal problems continues to pervade and perplex the law today. Perhaps nowhere is that tension more pronounced and more troubling than in family law. It is probably impossible to practice family law without wrestling with the imponderable choice between rules and discretion. Consider, for example, how many areas of family law are now being fought over in-just those terms. For decades we have lived with an abundantly discretionary way of resolving child-custody disputes: The best-interests-of-the-child standard has long been understood to give judges acres of room to roam. Yet in recent years scholar after scholar has inveighed against the discretionary scope that standard permits judges, and jurisdiction after jurisdiction has adopted one or another standard-the primary caretaker presumption or joint custody, for instance-intended to cabin, crib, and confine the range of judicial discretion. Judicial discretion has also been the target of recent reforms in the law of child support. As social determination to charge fathers with the costs of rearing their children has intensified, so has dissatisfaction with the way judges have exercised their very considerable discretion in setting child support obligations. This dissatisfaction has resulted in federal requirements that states substitute relatively mechanical and limiting "guidelines" for judicial discretion.
Schneider, Carl E. "The Tension between Rules and Discretion in Family Law: A Report and Reflection." Fam. L. Q. 27 (1993): 229-45.