Investigative Detentions and the Constitution

Section 9 of the Charter provides that everyone has the right not to be arbitrarily detained. A detention will not be arbitrary if it is lawful. 
One type of lawful detention is a common law investigative detention. This power allows the police to detain people for investigation “if there are reasonable grounds to suspect in all the circumstances that the individual is connected to a particular crime and that such detention is necessary.” However, the investigative detention must be “brief in duration” and conducted in a reasonable manner.
R. v. Mann, 2004 SCC 52, [2004] 3 S.C.R. 59, at para. 45.

All Investigative Detentions Must Be Brief
The permitted duration of an investigative detention is determined by considering whether the interference with the suspect’s liberty interest by his continuing detention was more intrusive than was reasonably necessary to perform the officer’s duty, having particular regard to the seriousness of the risk to public or individual safety. 

 R. v. Clayton, at para. 31;
R. v. Mann, at p. 324; 
R. v. Aucoin, 2012 SCC 66, [2012] 3 S.C.R. 408, at para. 36.

However, an investigative detention that is not brief cannot be constitutionally sustained.

The purpose of the brief detention contemplated under the investigative detention power is to allow the police to take investigative steps that are readily at hand to confirm their suspicion and arrest the suspect or, if the suspicion is not confirmed, release the suspect.  

R. v. Barclay, 2018 ONCA 114, at para. 29. 

“Brief” describes a range of time, not a precise limit.  While all investigative detentions must be brief, the permitted duration of an investigative detention is case-specific and is informed by a number of factors (set out in R. v. Barclay, 2018 ONCA 114, at paras. 31, 32) including the following:

1.       The intrusiveness of the detention
The more intrusive the detention is to the suspect’s liberty interest, the more closely its duration will be scrutinized.

2.      The nature of the suspected criminal offence.

If the suspected offense is not serious, the permitted duration will probably be at the shorter end of “brief”.
3.      The complexity of the investigation.

If the investigation is not complex, one would expect that police questioning of the suspect would not reasonably need to be lengthy, and the permitted duration will probably be at the shorter end of “brief”. However, if the investigation of the suspected criminal offence is complex, its complexity will only justify a longer permitted duration within the range of “brief” to the extent it is causally linked to the duration of the detention.

4.      Any immediate public or individual safety concerns.

 Immediate public or individual safety concerns may justify a permitted duration at the longer end of “brief”.
5.      The ability of the police to effectively carry out the investigation without continuing the detention of the suspect.

 If there are other reasonable means of continuing the investigation without detaining the suspect, the continued detention of the suspect would likely render continued detention unconstitutional.

6.      The lack of police diligence.

7.      The lack of immediate availability of the required investigative tools.