The improper joining of a party to a criminal or civil lawsuit. In federal civil cases, Federal Rules of Civil Procedure Rule 21 governs misjoinder. A party is considered misjoined if joining them to a case violates permissive joinder under Federal Rules of Civil Procedure Rule 20. Thus, a party is misjoined if the alleged claim against them does not arise out of the same transaction or occurrence as other defendants, and there are no common questions of law or fact. A party who is misjoined may, at any time, move for the court to drop her from the suit under FRCP 21 or the court may drop a party on its own. However, misjoinder is not grounds for dismissal of the case in its entirety.
In federal criminal cases, Federal Rules of Criminal Procedure 8 governs. A defendant is misjoined in a criminal case if the charged offense is not of the same character, is not based on the same act or transaction, or is not connected with a common scheme as other defendants. Additionally, under Federal Rules of Criminal Procedure 14(a), a court may order separate trials or grant a severance of defendants if joining a defendant in a case would unfairly prejudice any of the parties.
[Last updated in July of 2020 by the Wex Definitions Team]