Layer two overview: Cases, Orders, Opinions, Decisions and Writings

The words "decision", "order", "opinion", and "judgment", and even "case" tend to be used both loosely and interchangeably to mean either the act that delivers a court's ruling in a particular case, or the text of the ruling itself. To make things even more confusing, a decision (in either sense) may affect (either dispositively or nondispositively) more than one case, and a decision (in the sense of the text that records the court's ruling) may consist of more than one document.

For our purposes here:

Relationship to identifiers

A careful reading of the definitions above will show that there are a number of many-to-one and many-to-many relationships involved in a single decision. This has two important implications:

The US Supreme Court resolves these issues by choosing one docket number from among the cases decided as the identifier for the decision, and using a system of file extensions to identify different opinions that are part of the same decision.

Finally, the identifiers traditionally used for American caselaw -- citations to printed books published by a particular vendor -- are not unique. They refer to page locations in which more than one case can be found, and should be thought of as finding aids rather than unique identifiers.