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

Terminology

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:

• A case is a dispute among two or more parties.  It is usually brought in a trial-level court (though some cases begin in the courts of appeals), and it can traverse up and down the court hierarchy, with multiple periods in the trial court, court of appeals, and even the Supreme Court. 
• An order tells the parties to a case or cases something that they should do.  Orders can deal with housekeeping matters, such as scheduling or permission to file a brief, or with something substantive and important, such as whether the case will be dismissed or not.  An order may accompany an opinion or opinions, but if it does not, it tends to be brief and not to offer reasons. It may deal with one or more cases, and may dispose of those cases or not.
• A decision is a loose term for the set of opinions that accompany an order, combined with that order.  There may be more than one case associated with a particular decision.    
• An opinion is a general term describing the written views of a judge or judges with respect to a particular order.  Not all orders--including important orders, and including in both the district courts and the courts of appeals--have opinions.  A single order by a court might produce a zero or more majority opinions, zero or more concurring opinions, zero or more dissenting opinions, and zero or more opinions that concur in part and dissent in part.  It is also possible that a decision produces other documents that are not opinions -- for example, a syllabus, appendix, or summary describing all the other documents related to the decision.
• A writing is a single document forming all or part of an opinion. For our purposes here, it is a single computer file.
 

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:

• First, most if not all of the identifiers assigned to cases at earlier stages of the judicial proceeding are unsatisfactory for use as permanent identifiers for the decision, since there may be more than one case one associated with a particular decision, and more than one decision associated with a particular case. Docket numbers or other case-tracking identifiers are particularly deceptive in this respect, because (in decisions that dispose of multiple cases) more than one will be associated with a decision, and because some courts recycle them from session to session or year to year.
• Second, decision identifiers (on their own) are not necessarily good identifiers for writings, as there may be more than one writing associated with a decision.  Some courts bundle all the different opinions (majority, concurrences, dissents) into a single writing (one computer file).  Others issue them separately. 

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.