The collateral order doctrine is an exception to the general rule against allowing interlocutory appeals (appeals on a temporary order issued during the course of litigation). This doctrine traces its origins to the case Cohen v. Beneficial Loan Co.
As a general rule, only final judgements are appealable. Nonetheless, as noted in Cohen v. Beneficial Loan Co., some interlocutory decisions act as final judgments to certain rights. Therefore, interlocutory decisions are appealable under the collateral order doctrine if they fulfill three conditions:
- The interlocutory decision conclusively determined the disputed question
- The disputed question is important and entirely separable from the merits of the action
- The interlocutory decision is effectively unappealable after a final judgment is handed down
For example, in Cohen an interlocutory decision regarding whether a New Jersey statute which required parties to offer a security interest before trial is applicable in federal court was subject to the collateral order doctrine and could therefore be appealed before the trial’s conclusion.
[Last updated in July of 2022 by the Wex Definitions Team]