What is the difference between terminology used in legal actions that refer to the parties in an action?

Lisa Sherman
California Labor & Employment Attorney

Various terminology is used in legal actions to refer to parties, such as, “plaintiff/petitioner/complainant/claimant/defendant/appellant/respondent..."  So what do they mean? 

There are subtle differences between the use of these terms. 

Plaintiff : A Plaintiff is usually the person who files a legal action against a Defendant. 

Defendant: A Defendant is usually the person who is alleged to have engaged in unlawful conduct by the Plaintiff. 

Claimant: An arbitration is an alternative to a trial in a courtroom.  The Plaintiff is referred to in arbitration as the Claimant.  Petitioner: A Petitioner is typically the person who files a petition against a Respondent seeking some sort of immediate relief from a tribunal. 

Respondent: A Defendant in an arbitration is referred to as a Respondent.  However, a Respondent can be either a Plaintiff or Defendant in an appeal from the lower court, depending on who won the case.  A person becomes a Respondent when the losing party (Appellant) from the initial case appeals from the decision of the lower court.

Appellant: the party initiating an appeal. 

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