Judicial precedent refers to a process in which decisions in legal cases are used to set a standard for cases thereafter. Lower courts are supposed to be bound by the decisions made in superior courts. Not following the prior standards is not supposed to be an option for a court. There are, however, certain techniques that can allow judges to avoid precedents. This system is generally attributed as originating from English law.
Stare decisis is a Latin term that can be translated as to stand upon decisions. This is the underlying principle of judicial precedent. According to this rule, if a legal question has already been answered or interpreted, that decision should be used in all cases involving the same question thereafter. Superior court decisions can reverse precedents that have developed in lower courts. When decisions are made by superior courts, however, these decisions are binding and must be respected by all inferior courts in that jurisdiction.
In legal systems where judicial precedent is used, one of the primary motives is consistency. The law is not meant to be a matter of personal whim but rather a system based on solid, justifiable principles. Judicial precedent makes the legal system consistent. When there is inconsistency in a legal system, justice is generally considered to be jeopardized.
Consistency is not the only advantage of judicial precedent. This system also provides a measure of predictability. As decisions made in the past can be reviewed ahead of a trial, it is often possible to predict or to make an educated guess as to what the outcome will be.
One case can only be considered a precedent for another if the legal question involved is the same. For example, a case may determine that making traffic stops based on perceptions of race and criminality is a violation of civil rights and therefore that any resulting charges must be dismissed. In all other cases where this issue arises, this conclusion should be applied.
For judicial precedent to apply, there generally needs to be similarity between the cases involved. The facts in two cases do not need to be identical, but they must be relevant. Judges may sometimes use this as a loophole to escape a binding decision. They can do this by considering the facts in one case to be different enough from those in another that the older case is not relevant and therefore is not binding as a precedent.