Petitioner

A petitioner is a person or organization who submits a petition—a formal written request—to a court, government agency, or other authority seeking relief, a legal remedy, or a change in status. The term is used across civil, administrative, and constitutional proceedings. A petition may seek outcomes such as a court order, a license, or the reversal of a decision, and it may initiate or drive a legal or administrative process.

Usage varies by jurisdiction. In many court cases, the petitioner is the party who initiates the proceeding by filing a petition. In family law, for example, the spouse who files for divorce is the petitioner, while the other spouse is the respondent. In appellate practice, the petitioner is the party who files the petition or notice of appeal to obtain review of a decision, with the other party acting as the respondent or appellee. In administrative settings, a petitioner is someone who files for immigration benefits, a permit, or other relief with a government agency.

Origin and scope. The term derives from Latin petitio, meaning “a request” or “plea.” Not all legal systems use “petitioner” to label a party; some use plaintiff, applicant, claimant, or appellant depending on the context. Regardless of jurisdiction, the petitioner is typically defined by presenting a petition to an authority in pursuit of relief, action, or status change.