10. Everyone has the right on arrest or detention:
a. to be informed promptly of the reasons therefor;
Similar provisions may be found in the following Canadian laws and international instruments that are legally binding on Canada: paragraph 2(c) of the Canadian Bill of Rights; and article 9(2) of the International Covenant on Civil and Political Rights.
See also the following international, regional and comparative law instruments that are not legally binding on Canada but include Similar provisions: article 7(4) of the American Convention on Human Rights; and article 5(2) of the European Convention for the Protection of Human Rights and Fundamental Freedoms.
Paragraph 10(a) is founded on a double rationale. First, there is the notion that one is not obliged to submit to an arrest without knowing the reasons for the arrest. A person needs to know the reasons for an arrest in order to decide whether to submit to it. Second, this right recognizes that an individual must fully understand the reasons for his or her arrest or detention — and thus the extent of his or her criminal jeopardy — if the individual is to meaningfully instruct counsel and thus exercise the paragraph 10(b) Charter right (R. v. Evans,  1 S.C.R. 869 at paragraph 31; R. v. Borden,  3 S.C.R. 145 at paragraph 44).
1. What constitutes “arrest” or “detention”?
See the general discussion of section 10.
2. What does it mean “to be informed”?
In determining whether an arrested or detained individual is properly informed, the question is whether what the individual was told, viewed reasonably in all the circumstances of the case, was sufficient to permit him or her to make a reasonable decision with respect to whether to submit to arrest and to be able to instruct counsel under paragraph 10(b) of the Charter. It is the substance of what the accused can reasonably be supposed to have understood, rather than the formalism of the precise words used, which must govern (Evans, supra at paragraph 35; R. v. Smith,  1 S.C.R. 714 at 728). “Common parlance” may be used in communicating the extent of the accused’s jeopardy (Smith, supra).
The individual need not be aware of the precise charge faced or all the factual details of the case (Smith, supra at 728).
The individual should be informed of the true purpose of the investigation, although the police do not have to tell a person who has provided unambiguous consent that a sample may be used in future investigations which are not yet contemplated (Borden, supra at paragraph 45; R. v. Arp  3 S.C.R. 339 at paragraphs 85-88).
If an officer informs a person that he or she is “detained”, and adequately provides the reasons, the person’s rights under paragraph 10(a) are not infringed even if the person is not explicitly told that the person is under “arrest” or that the person could be charged with murder (R. v. Latimer,  1 S.C.R. 217 at paragraphs 30-31). Individuals who are detained under the common law power of investigative detention must be advised, in clear and simple language, of the reasons for the detention (R. v. Mann,  3 S.C.R. 59 at paragraph 21).
3. How soon is “promptly”?
Whether it is possible to delay the implementation of paragraph 10(a) rights under exceptional circumstances remains an outstanding issue (R. v. Mian,  2 S.C.R. 689 at paragraph 74). In Mian, the Supreme Court did not consider the delay by the police in complying with their section 10 informational duties, in order to protect the integrity of a separate and ongoing investigation, to be the kind of exceptional circumstance that could be capable of justifying the suspension of section 10 rights (Mian, supra at paragraphs 74, 76).
There is no Supreme Court authority that directly establishes the meaning of “promptly” in paragraph 10(a), and whether it would be different from the timeliness requirement in paragraph 10(b), which must be fulfilled “without delay”. However, the fulfillment of paragraph 10(a) is considered a prerequisite for the meaningful exercise of paragraph 10(b), and the Supreme Court indicated that paragraph 10(b) must be fulfilled immediately (R. v. Suberu,  2 S.C.R. 460 at paragraphs 41-42). Prompt fulfillment of paragraph 10(a) means providing this information immediately upon arrest or detention, interpreted in light of the surrounding circumstances (R. v. Nguyen, 2008 ONCA 49 at paragraph 20; R. v. Kelly,  O.J. No. 2 (Ont. C.A.); R. v. Boden, 2014 BCSC 66 at paragraphs 53, 65).