Duhaime's Law Dictionary

Investigative Detention Definition:

The brief detention of an individual by a police officer for investigative purposes.

Related Terms: Arrest, Search

In R v. Clayton, Justice Rosalie Abella of the Supreme Court remarked that the appeal before the Court raised "serious issues of crime, public safety and civil liberties" and that "there does not exist in Canada a general police power of investigative detention. R. v. Mann so held."

But she then added: "Parliament is the appropriate body to consider and enact measures that lay down the particular circumstances in which investigative detention is permitted. However, Parliament has not yet enacted a law governing the police response to a situation such as we have in this case. Resort must therefore be had to the common law powers of the police, an area of the law beset with both uncertainty and controversy."

In that 2004 decision of the Supreme Court of Canada, R v Mann, the same Court, with Justice Frank Iacobucci writing for the majority,  used these words at ¶27-45:

"… a power of search incidental to investigative detention does exist at common law.

"The Court of Appeal for Ontario helpfully added … in R. v. Simpson … that investigative detentions are only justified at common law if the detaining officer has some articulable cause for the detention, a concept borrowed from U.S. jurisprudence. Articulable cause was defined … as … a constellation of objectively discernible facts which give the detaining officer reasonable cause to suspect that the detainee is criminally implicated in the activity under investigation.

"Articulable cause, while clearly a threshold somewhat lower than the reasonable and probable grounds required for lawful arrest is likewise both an objective and subjective standard….

"Justice (David) Doherty (of the Court of Appeal for Ontario, in Simpson) limited the scope of common law investigative detention by explaining that the articulable cause requirement was only an initial step in the ultimate determination of “whether the detention was justified in the totality of the circumstances…. The power to detain cannot be exercised on the basis of a hunch, nor can it become a de facto arrest.

handcuffs"To summarize, as discussed above, police officers may detain an individual for investigative purposes if there are reasonable grounds to suspect in all the circumstances that the individual is connected to a particular crime and that such a detention is necessary. In addition, where a police officer has reasonable grounds to believe that his or her safety or that of others is at risk, the officer may engage in a protective pat-down search of the detained individual. Both the detention and the pat-down search must be conducted in a reasonable manner. In this connection, I note that the investigative detention should be brief in duration and does not impose an obligation on the detained individual to answer questions posed by the police. The investigative detention and protective search power are to be distinguished from an arrest and the incidental power to search on arrest, which do not arise in this case."

In his 2013 treatise, Alec Fiszauf interprets the reasons of Justice Doherty in R v Simpson as as relying on both American and Canadian authorities, much of which is taken from R v. Mann, to refer to an investigative detention as:

"... an ancillary, common law power to detain for investigation in circumstances where the detaining officer can articulate grounds for reasonable suspicion that the accused is involved in criminal activity.

"The test is based on a constellation of objectively observed facts and not a hunch or intuition."


  • Fiszauf, Alec, The Law of Investigative Detention (Toronto: LexisNexis, 2013).
  • R. v. Clayton, 2007 SCC 32
  • R v Mann, 2004 SCC 52
  • R v Simpson, 79 CCC 3d 482 (ONCA)
  • Terry v Ohio, 392 US 1 (1968). In R v Mann op. cit, Justice Iacobucci wrote of American law:  "The United States Supreme Court held in Terry  that a police officer may seize an individual reasonably suspected of imminent or on-going criminal activity, ask questions of him or her, and perform a limited frisk search for weapons.  Subsequent jurisprudence requires the totality of the circumstances to be taken into account when determining that sufficient reasonable articulable suspicion of criminal activity exists to justify the seizure (United States v. Cortez, 449 US 411 (1981)).  The U.S. case law has evolved significantly since Terry.  Police authority was expanded in Adams v. Williams, 407 US 143 (1972), beyond imminent violent offences to possessory offences reported by reliable informants.  In 1980, United States v. Mendenhall, 446 US 544 (1980), the U.S. Supreme Court developed a no-seizure rule permitting brief detentions of individuals where reasonable suspicion is lacking.  Five years later, in United States v. Hensley, 469 US 221 (1985), the U.S. Supreme Court extended Terry and Adams to permit detention and questioning of persons suspected of involvement in completed felonies, where the suspicion was grounded in specific and articulable facts, on the basis of a public interest in investigating crime and safeguarding the public."

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