Duhaime's Law Dictionary

Proprio Motu Definition:

Latin: of one's own initiative.

Related Terms: Ex officio, Prosecutorial Discretion

In some legal relationships that work together within a legal context, it is often important to distinguish that a person or body acts of its own accord and not on the request or direction of another.

For example, a Court may take decisive action in a case before it of its own accord of its own volition, proprio motu, in extraordinary or exceptional circumstances.

Lakshman Marasinghe, professor of law at the University of Windsor (Canada) wrote of one significant area where the concept of proprio motu is core to a process but also described with reference to the Latin maxim: the powers of the prosecutor at the International Criminal Court to investigate and bring charges, or not, as against an individual suspected of international crimes.

proprio motuHe or she moves not on political direction or direction of the Court or its members but moves independently, of its own initiative only, proprio moitu:

"Article 15 (of the Rome Treaty which established the International Criminal Court) ... provides the Prosecutor with an unfettered power to trigger the Court's jurisdiction proprio motu, which means at his or her own initiative
without any formal referral act or formal duty to initiate.

"This language goes to the core ... insofar as it encapsulates the principle of prosecutorial independence."


  • Marasinghe, Lakshman, Proprio Motu Powers - The Prosecutor of the International Criminal Court, 22 Sri Lanka J. Int'l L. 195 (2010)
  • Mayrand, A., Dictionnaire de Maximes et Locutions Latines Utilisées en Droit, 4th Ed. (Montreal: Editions Yvon Blais, 2006), page 471

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