The term “interlocutory” is used to indicate a lack of finality. An interlocutory appeal is an appeal of a non-final order issued during the course of litigation.
The collateral order doctrine sets forth the rules for such appeals. Interlocutory appeals are extremely rare, and a three-part test determines whether the collateral order exception to res judicata makes such an appeal possible:
- The order must have conclusively determined the disputed question;
- The order must “resolve an issue completely separate from the merits of the action”;
- The order must be “effectively unreviewable on appeal from a final judgment.”
See also: Hallock v. Bonner, 387 F.3d 147 (2d Cir. 2004)
[Last updated in March of 2023 by the Wex Definitions Team]