A leading case is a court case which results in a decision which sets a precedent. It may establish a new legal concept or interpret a law in a new way. Leading cases contribute to the body of law and they are used by other lawyers and judges in the future when addressing similar matters. Some are familiar to members of the general public because they had such a profound impact on the legal field and on the culture of a society.
When judges hear cases, they weigh the information in the case against existing law and precedent to make a decision which they feel is in line with the existing legal system. Sometimes, this is not possible. A case may challenge an existing law, may argue for a reinterpretation of a law, or may be so unique in nature that no known precedent or law applies. In these cases, the decision made by the judge will involve setting a precedent. This allows the legal system to evolve as new situations arise and as the approach to law changes; for example, laws against miscegenation were once on the books in many nations and such laws are no longer deemed legal or appropriate.
Leading cases are the most important cases in a given area of law, setting the precedent which other legal scholars abide by. On occasion, the outcome of a leading case may be challenged by a lawyer or judge who disagrees with the outcome. When such cases are overturned, this in turn sets precedent, and threatens cases which hinged upon that leading case because their outcomes may no longer be valid either. Leading cases comprise part of case law, the body of law which is derived from legal decisions, rather than laws passed by the government.
Typically higher courts are involved in a leading case. A higher court may be called upon to reverse a lower court ruling, to clarify the interpretation of a law, or to take other actions which could result in setting a legal precedent. As a result, proceedings in higher courts tend to be followed closely when they concern controversial issues, as members of the media as well as the legal community want to know if the court will establish a leading case.
Some examples of leading cases include Law v. Canada (1999) in Canada, Fagan v. Metropolitan Police Commissioner (1969) in Britain, and Miranda v. Arizona (1966) in the United States.