ex rel.

The abbreviation ex rel. stands for the Latin phrase ex relatione . Ex relatione is a procedural phrase in the Bluebook , meaning "on the relation of", “out of the relation of”, or “on behalf of.”  This is a phrase showing that the plaintiff is suing based on information from another person. In the case caption, the party named after " ex rel ." is the party on whose information the suit is brought, this party is called the relator .  Many government lawsuits based on whistleblowers ' information are brought as suits ex rel .

[Last updated in September of 2022 by the Wex Definitions Team ]

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