I. SCOPE OF THE PROBLEM
The pervasiveness of this topic is illustrated by Appendix A, (1) a survey of volumes 658 and 659 of the Federal Reporter, Second Series. Statistical data at the conclusion of Appendix A indicate that approximately one-fourth of the total number of cases reported contained one or more issues in which trial-court discretion was subjected to scrutiny by appellate courts. As a result of this scrutiny, approximately seventy percent of the trial courts' actions were approved and approximately thirty percent were disapproved. These data correspond to other similar surveys undertaken.
Considerable discretion on the part of district and appellate courts is provided in the Federal Rules of Civil Procedure, Federal Rules of Criminal Procedure, and Federal Rules of Appellate Procedure, which include approximately fifty provisions that either explicitly or implicitly recognize the existence of discretion.
Thus, the topic of trial-court discretion is very wide. But the question remains: "Is it very deep?" My answer is equivocal: Good sense tells me that it ought to be. Surely a topic as pervasive as the exercise of judicial discretion is not an area about which it can be said that there is "no law at all" worth talking about. Nonetheless, it is true that judicial opinions almost invariably discuss the exercise of discretion by a court in a particular area as a discrete topic unrelated to other situations in which judicial discretion is recognized and exercised. Thus, while it is difficult to assert that general law pertaining to the exercise of judicial discretion exists, it is true that a great deal of particular law exists. Nonetheless, my purpose is to suggest that perhaps some useful generalizations are possible.
II. THE MEANING OF DISCRETION
To have discretion is to have choice. To have choice is to be able to choose one course of action over one or more others with immunity from reversal by a higher court because of the course selected. The range of choice is determined by the number of permissible courses of action that exist. This number may be as small as two or innumerable. The fewer the number of permissible choices, the more narrow the discretion; the greater the number, the wider the discretion.
This definition of discretion suggests a distinction between what might be called de jure discretion and de facto discretion: Immunity from reversal may exist because the choice made was permissible or because even though the choice was impermissible, reversal would be improper. An example of the former is the proper exercise of discretion in response to a request for a continuance. An example of latter is an application of the harmless error doctrine. Our concern is with de jure discretion.
III. WHY MUST THE TRIAL COURT BE GIVEN DISCRETION?
Discretion is indispensable, first, because rules for every contingency cannot, and should not, be formulated. It is also indispensible because the trial court is better able to fashion the appropriate response to a specific fact situation than is an appellate court acting either before (by having fashioned a general rule in prior cases raising a similar issue) or after (by fashioning a general rule in the course of its present review) the trial court's exercise of its discretion. (2) And finally, discretion is indispensible because it contributes substantially to a proper division of labor between trial courts and appellate courts.
IV. SOME TYPES OF ISSUES BEST LEFT TO TRIAL-COURT DISCRETION
Issues that pertain to the details of the management of a trial are one example of those best left to the discretion of the trial court, and might include motions to sever; whether to permit use of expert testimony; management of voir dire; and time of proof of conspiracy where a co-conspirator statement is offered as an admission under Rule 801(d)(2) of the Federal Rules of Evidence. …