Landmark court decisions, in present-day common law legal systems, establish precedents that determine a significant new legal principle or concept, or otherwise substantially affect the interpretation of existing law.
In common law legal systems, a precedent, or authority, is a principle or rule established in a previous legal case that is either binding on or persuasive for a court or other tribunal when deciding subsequent cases with similar issues or facts.
A common law legal system is characterized by case law developed by judges, courts, and similar tribunals, when giving decisions in individual cases that have precedential effect on future cases.
Law is a system of rules that are enforced through social institutions to govern behavior.
US Supreme Court Landmark Cases by Mr. Raymond's Civics and Social Studies Academy
"Leading case" is commonly used in the United Kingdom and other Commonwealth jurisdictions instead of "landmark case" as used in the United States.
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom or Britain, is a sovereign country in western Europe.
7 Landmark Court Cases that Changed Indian Laws by Mind Boggler
In Commonwealth countries, a reported decision is said to be a leading decision when it has come to be generally regarded as settling the law of the question involved.
In 1914, Canadian jurist Augustus Henry Frazer Lefroy said "a 'leading case' [is] one that settles the law upon some important point."
Distinguishing a new principle that refines a prior principle, thus departing from prior practice without violating the rule of stare decisis;
In law, to distinguish a case means a court decides the holding or legal reasoning of a precedent case will not apply due to materially different facts between the two cases.
Establishing a "test", such as the Oakes test or the Bolam test.
Sometimes, with regard to a particular provision of a written constitution, only one court decision has been made.
By necessity, until further rulings are made, this ruling is the leading case.
For example, in Canada, "[t]he leading case on voting rights and electoral boundary readjustment is Carter.
Canada is a country in the northern half of North America.
In fact, Carter is the only case of disputed electoral boundaries to have reached the Supreme Court."
The degree to which this kind of leading case can be said to have "settled" the law is less than in situations where many rulings have reaffirmed the same principle.