Prior to any critical evaluation of the murky waters upon which the investigative detention vessel sails, a brief account of its legal evolution is helpful. Investigative detention has a well-established historical pedigree in continental European and in socialist legal jurisdictions. The powers found in these jurisdictions may exceed the acceptable bounds for Canadian law enforcement; however, they are worth noting. The legislative schemes in foreign jurisdictions such as Ireland, Scotland, Russia, France and China all permit stationhouse detention based upon less than probable cause, and it may be that this onerous form of detention has no place in the Canadian criminal process. However, it must be recognized that investigative detention refers not only to these full-scale deprivations; it also encompasses briefer, less intrusive street detentions for investigatory purposes. Closer to home, investigative detention was legitimized in the United States in the late 1960s with the advent of the “stop and frisk” doctrine. The U.S. Supreme Court held that a police officer may seize an individual reasonably suspected of imminent or on-going criminal activity, ask questions of him, 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.
It is also important to identify the conditions which led to the introduction of investigative detention as a natural evolution of the administration of law enforcement in the North American context. In contemporary times, the law enforcement function of the police has been the most emphasized, even though it may not consume most of an officer’s time. Attempting to cultivate an image of professional specialization, the police have “created an image of the expert crime-fighter despite an inability to effectively control crime.”
"The police have claimed to prevent, control, deter, and punish crime and have made that above all their primary legitimating theme. They have in recent years grown in strength, power and authority. They have done this in spite of the fact that they cannot control crime."
In light of this self-created image and the ever-increasing crime rate of this century, the police came to recognize the importance of aggressive preventive patrol. As crime prevention became less passive, an emphasis on solving problems before crime grew out of them evolved. While the primary justification for such investigative work may be the apprehension of suspects for arrest and prosecution, frequent field stops, particularly in high crime areas, are intended to make it known that the police are omnipresent, thereby deterring potential offenders from committing crimes. Hence, street interrogations of persons whose appearance and actions arouse the suspicion of alert patrolmen were deemed important patrol tasks.
The indisputable turning point in Canadian law was the 1993 Ontario Court of Appeal case R. v. Simpson. Prior to Simpson, the law seemed relatively clear. The police had only two options when dealing with persons they suspected of wrongdoing: arrest or release.
"Short of arrest, the police have never possessed legal authority at common law to detain anyone against his or her will for questioning, or to pursue an investigation.... police lack legal authority to detain a person for questioning or for purposes of investigation at common law, even on suspicion, short of arrest."
However, the Simpson Court recognized that, despite a lack of formal authority, investigative stops were a routine part of police patrol practices. In an effort to “regulate” such encounters, the Court employed a cost-benefit analysis, balancing individual liberty rights and privacy interests with a societal interest in effective policing. In recognizing a police power at common law to detain for investigative purposes, the Simpson Court relied upon the Supreme Court of Canada’s earlier endorsement of a doctrine borrowed from English jurisprudence - the ancillary powers doctrine - an instrument by which courts could vest the police with those ancillary powers that would assist them in the fulfillment of their broad duties. The resulting doctrinal interpretation led the Court to find that in situations where the police have articulable cause to believe that an individual is implicated in criminal activity, they are authorized to briefly detain that person for investigative purposes. The Court defined “articulable cause” as having reasonable grounds to suspect that the detainee is criminally implicated based on “a constellation of objectively discernible facts.”
The Supreme Court of Canada subsequently endorsed the Court of Appeal’s treatment of investigative detention the 2004 case R. v. Mann. The highest court attempted to clarify the appropriate requirements for the use of investigative detention by changing the standard from “articulable cause” to “reasonable suspicion.” However, as a second step, the detention also had to be justifiable based on an assessment of “the totality of the circumstances.” It held that
"…the detention must be viewed as reasonably necessary on an objective view of the totality of the circumstances, informing the officer’s suspicion that there is a clear nexus between the individual to be detained and a recent or on-going criminal offence."
 Young, supra.
 Terry v. Ohio, 392 U.S. 1 (1968).
 United States v. Cortez, 449 U.S. 411 (1981).
 R. Ericson, Reproducing Order: A Study of Police Patrol Work (Toronto: University of Toronto Press, 1982).
 P. K. Manning, Police Work: The Social Organization of Policing (Illinois: Waveland Press Inc., 1977, 1997
 Young, supra.
 D. Bayley, "Police Function, Structure and Control in Western Europe and North America: Comparative and Historical Studies" in N. Morris & M. Tonry, eds, Crime and Justice, vol. 1 (Chicago: University of Chicago Press, 1979).
 D. Strauss, “Field Interrogations: Court Rule and Police Response” (1972) 49 J. Urb. L.
 O.W. Wilson, Police Administration, 2d ed. (New York: McGraw-Hill, 1963).
 R. v. Simpson (1993), 12 O.R. (3d) 182.
 Dickson J in Simpson, supra.
 Stribopoulos, supra.
 R. v. Simpson, supra.
 R. v. Mann (2004) 3 S.C.R. 59.
 J. R. Marin, “R. v. Mann: Further Down the Slippery Slope” (2004) 42 Alta. L. Rev.
 Iacobucci J in R. v. Mann, supra.