The essence of nomocracy, the rule of law, is limitation of the discretion of officials, and providing a process by which errors or abuse of discretion can be corrected. Some discretion is unavoidable, because law cannot anticipate every eventuality or how to decide which law may apply to a given situation. What guidance the law cannot provide is supposed to be provided by standard principles of justice and due process, reason, and the facts of each case. Ideally, officials should be mutually consistent and interchangeable, making similar decisions in similar cases, so that no one can gain an undue advantage by choosing the official or exercising undue influence on the official or on the process he operates. We trust officials to exercise such discretion as they have with wisdom, justice, and competence, to avoid government that is arbitrary, insolent, discriminatory, prejudiced, intrusive and corrupt.
Within the public sector, discretion can be exercised by legislative, executive, or judicial officials. Within the private sector, discretion may be exercised by private officials, such as agents, trustees or corporate officers, who are in principle subject to the supervision of the courts. The focus here is on judicial discretion, and the abuse of it. It will not discuss every area of judicial discretion.
The first major check on the discretion of judges was the jury. A judge, holding office over the course of multiple cases, and selected by appointment or election, is susceptible to undue influence. A jury, chosen by sortation, or lot, for a single case, just before the case, is less likely to be corrupted, and having multiple jurors render verdicts collectively provides a check by each on the others. What they might lack in knowledge of the law is offset by their connection to the non-legal environment in which most people subject to the law must operate.
In courts that try to save time and money by not using juries, such as family courts in some states, complaints about abuse of judicial discretion have led to calls for juries to decide questions of custody, visitation, child support, and the distribution of marital property.
Judges who impose lenient sentences, to avoid prison overcrowding and the early release of violent offenders, often provoke demands for mandatory minimum sentences or sentencing guidelines that reduce their discretion to do things like impose reduced sentences on defendants thought to be remorseful or unlikely to commit another offense.
Most complaints of abuse of judicial discretion, and calls to limit it with more laws, concern questions of policy or equity. But there is another broad category, which concerns constitutional questions of due process and civil rights. This is too large a field to discuss adequately in a short article, so only a few of the more important kinds of judicial discretion that are often being abused will be presented.