Canadian Criminal Evidence/Testimonial Evidence/Competence and Compellability
Who can be a witness at a trial depends on two factors, competence and compellability.
The competence of a witness refers to whether a witness is legally permitted to testify and give evidence. The compellability of a witness refers to the power to force a competent witness to testify even if it's against their will.
At common law, all individuals are presumed competent to testify so long as their information is relevant barring certain groups of people. Historically, the common law prevented many types of people from testifying. This included convicts, infants, the insane, marriage, and lack of belief in a higher power. Many of these rules have been overturned by statute, for example, the rule against convicts was removed under by section 12 of the CEA. Their record, however, can be used as character evidence.
The three classes of exceptions that remain today are children, people of low mental capacity, and spouses. In each of these it is up to a challenger to establish the incometence of the witness.
A witness is presumed to possess both capacity and responsibility. More specifically, to testify, a witness need only be able to # observe,
- recall his or her observations accurately,
- communicate his or her recollections.
In order to communicate the witness must be able to understand and respond to questions, and the witness must have the moral responsibility to speak the truth.
A witness who states that they may not tell the truth is still competent to testify. Such issues of truthfulness are factors of credibility for the trier-of-fact.
A witness is barred by foreign law to testify is still competent.
- R v Ferguson (1996) 112 CCC (3d) 342 (BCCA)
- R v Steinberg,  SCR 421
- R v Walsh, (1978) 48 CCC (2d) 199 (ONCA)
- R v Spence  2 SCR 278
A competent witness is generally a compellable witness.
But a incompetent witness is generally not compellable.
Section 698 allows the ordering of a subpoena requiring a witness to attend court:
698. (1) Where a person is likely to give material evidence in a proceeding to which this Act applies, a subpoena may be issued in accordance with this Part requiring that person to attend to give evidence.
(2) Where it is made to appear that a person who is likely to give material evidence
- (a) will not attend in response to a subpoena if a subpoena is issued, or
- (b) is evading service of a subpoena,
a court, justice or provincial court judge having power to issue a subpoena to require the attendance of that person to give evidence may issue a warrant in Form 17 to cause that person to be arrested and to be brought to give evidence.
(3) Except where paragraph (2)(a) applies, a warrant in Form 17 shall not be issued unless a subpoena has first been issued.
The key factor is that the issuing party must be able to establish that the witness would likely or probably have material evidence to give. It is not enough that the witness "may have" material evidence.
Where the subpoena is not valid it may be quashed by a superior court judge.
A judge has a discretion to excuse an expert witness who is under a valid subpoena.
Where the matter is before a provincial court judge and the person is within the province, a provincial court judge may order their attendance by issuing a subpoena under s.699(2)(a). However, under s. 699(2)(b), where the witness is out of province, either a provincial court a superior court judge may order the subpoena.
Where the matter is before a superior court judge, only that court may issue a subpoena compelling attendance (s. 699(1)).
- R v Schell (2004) 188 CCC (3d) 254 (ABCA)
R v Czipps (1979) 48 CCC (2d) 166 (ONCA)
- R v Harris (1994) 93 CCC (3d) 478 (ONCA)
- R v A  1 SCR 995
- R. v. Blais, 2008 BCCA 389
Missing Witnesses 
Section 705 gives authority of a court to issue a warrant of arrest for a witness who fails to attend on a subpoena.
Warrant when witness does not attend
705. (1) Where a person who has been served with a subpoena to give evidence in a proceeding does not attend or remain in attendance, the court, judge, justice or provincial court judge before whom that person was required to attend may, if it is established
- (a) that the subpoena has been served in accordance with this Part, and
- (b) that the person is likely to give material evidence, issue or cause to be issued a warrant in Form 17 for the arrest of that person.
Warrant where witness bound by recognizance
(2) Where a person who has been bound by a recognizance to attend to give evidence in any proceeding does not attend or does not remain in attendance, the court, judge, justice or provincial court judge before whom that person was bound to attend may issue or cause to be issued a warrant in Form 17 for the arrest of that person.
Warrant effective throughout Canada
(3) A warrant that is issued by a justice or provincial court judge pursuant to subsection (1) or (2) may be executed anywhere in Canada.
R.S., 1985, c. C-46, s. 705; R.S., 1985, c. 27 (1st Supp.), s. 203.
A judge has the inherent authority to order any person present in court to be compelled to testify where:
- the person has relevant evidence to give
- a party requires that person to testify in the proceeding
Similarly, an inmate witness can also be compelled to testify by way of s. 527.
Where a witness fails to attend, the judge has a discretion to order a witness warrant where he is satisfied that:
- proper attempts to serve the witness have been made;
- the witness is a material witness.
- R v Ayres (1984) 15 CCC (3d) 208 (ONCA)
- R v Scott  3 SCR 979
Oaths and Affirmations 
Common law requires all witnesses to take an oath to solemnify the evidence given. The implicit threat of divine intervention does not have the same weight as it did historically. As Justice Dickson stated in R. v. Bannerman, "[t]he object of the law in requiring an oath is to get at the truth relative to the matters in dispute by getting a hold on the conscience of the witness." Thus, there is a second option provided to allow people to opt for taking an affirmation of solemnity. This is provided under section 14 of the Canada Evidence Act (CEA) as well as under most provincial evidence acts. The form of the ceremony can vary. It can even be as simple as asking "do you know that it is a criminal offence to intentionally give false evidence in a judicial proceeding? Do you solemnly promise to tell the truth in this proceeding?"
The key to a proper oath or affirmation is that the witness understands what they are swearing to. Typically, it is not a problem with the exception when dealing with Children and witnesses of low mental capacity as will be seen later.
Children and Mental Capacity 
Rules surrounding the testimony of children is of particular importance. The reason for this is that children tend to be highly susceptible to influence, their ability to interpret events often affects their testimony, they may not understand the consequences of their actions, and they typically have a higher degree of credibility to a trier of fact.
At common law there is no minimum age for testimony. However, invidividuals of "tender years" (i.e. under fourteen) must be tested to see if they "possessed sufficent intelligence" to be considered competent, and understand the "nature and consequences" of an oath. If they were not able to understand the meaning of the oath they would usually be allowed to give unsworn testimony so long as the evidence they gave could be corroborated.
In regards to the understanding of the oath, Justice Dickson, in R. v. Bannerman stated that "all that is required when one speaks of an understanding of the "consequences" of an oath is that the child appreciates it is assuming a moral obligation." This test remains the common law requirement for an oath and still applies for civil trials in provinces that have not adopted the recent changes seen the CEA.
Section 16 
Section 16(1) of the CEA, was introduced in 1987 had changed much of the rules for children and people of low mental capacity. Much of the common law rules are preserved.
The common law presumption of competence is preserved, subject so section 16(1), which states:
16(1) Where a proposed witness is a person under fouteen years of age or a person whose mental capacity is challenged, the court shall, before permitting the person to give evidence, conduct an inquiry to determine
(a) whether the person understands the nature of an oath or a solemn affirmation; and
(b) whether the person is able to communciate the evidence.
An inquiry, in the form of a voir dire, is undertaken for any child witness or if the witness' capacity is challenged under section 16(6). Unless there is a possibility of prejudicing the jury, typically the inquiry is done in front of them, so that they can judge the degree of credibility that should be allocated to the witness. The inquiry usually involves questioning the witness (R. v. Parrott) by the judge and often with support of an expert. Nevertheless, the decision is the judge's to make.
The inquiry involves two steps. The individual must be shown the "understand the nature of an oath or solemn affiration", and secondly, must be shown to "communicate the evidence".
In the case of R. v. Marquard (1993) the Supreme Court considered the case of an unsworn child and whether she was able "to communicate" by the standard of section 16(1). The Court held that the inquiry need only examine the capacity of the witness to communicate and not their ability to observe and recall. Nevertheless, it is important to "explore in a general way whether the witness is capable of perceiving events, remembering events, and communicating events to the court", but whether the child remembers anything specific to the case is not necessary. L'Heureux-Dube, in dissent, argued against a special standard for children, which, with the imminent introduction of section 16.1 will be the view that prevails.
In R. v. Leonard (1989) the court examined the first question on whether the child understood the oath. They held that the issue revolves around "responsibility", it must be determined that the witnesses conscience is affected, and whether they approcate the significance of testifying. The court gave a four-part test to determine if the child understood the meaning of oath. The child must have:
- an appreciation of the solemnity of the occasion;
- an understanding of the added responsibility to tell the truth over and above the duty to tell the truth as part of ordinary duty of normal social conduct;
- an understanding of what it means to tell the truth in court;
- an appreciation of what happens, in both practical and moral sense, when a lie is told in court.
If the child passes this test then they will be allowed to testify under section 16(2) of the CEA.
However, in the event that the child does not understand the meaning of the oath they are still able to give an unsworn testimony under section 16(3) on the condition that they promise to tell the truth. There is an additional test that must be applied in order to accept a promise to tell the truth. The individual must understand what it means "to promise" and understand what it means to "tell the truth". The test for the truth is neither exact or demanding. It mostly involves having the child "commit" to telling the truth as they understand it in everyday social conduct. The distinction of this from the test to determine if the child understands the oath is that there is no requirement for the child to understand the solemnity of the court and does not need to understand their duty beyond everyday meaning of it.
For all unsworn testimony, in R. v. Kendal, the Court held that whenever a child gives sworn testimony the judge must warn the jury regarding the dangers of convicting based on a child's testimony. This practice is applied in any event to witnesses who give inconsistent evidence.
In comparasion wit the common law requirement for corroboration, section 16(3) removes this.
section 16.1 
By the end of 2005 an amendment Bill C-2 to the CEA is expected to go through which will substantially reduces the rules preventing testimony of children. Most significantly, the presumption against competence of children has been removed. If there is no challenge, any child under the age of fourteen may testify. In the event of a challenge the burden will be on the challenger to prove:
- that the child cannot understand and respond to simple questions
- that the child will not promise to tell the truth (s.16.1(6))
The first step lowers the bar set by Marquard and only requires that they are able to communicate. The second step is a substitute for the need to take an oath or affirmation. If the child promises to tell the truth it will be as good as an oath (s.16.1(8)). When challenging the second step, however, the challenger is not allowed to ask about the "nature" or "meaning" of what it means to tell the truth.
Spousal Immunity 
At common law a spouse of an accused is incompetent to testify except where the charge involves the person, liberty, or health, of the spouse.
The reason behind this is to support marital harmony.
The Canada Evidence Act has added further exceptions allowing the spouse to be competent and compellable for the Crown and co-accused:
- when called by the defence spouse (s 4(1) CEA)
- when the accused is charged with a listed offence which implicate the health and security of the spouse(s 4(2) CEA)
- when the accused is charged with a listed offence and the victim is under the age of 14 (s 4(4) CEA)
- the accused is charged with an offence involving danger to the spouse's "person, liberty, or health", b) when the accused threatened to the spouse's "person, liberty, or health", or c) violence, cruelty or threats are made against the spouse's child. (s 4(5) and the common law)
Thus, generally speaking spouse cannot testify on behalf of a co-accused or the crown. In civil trials, provincial evidence acts have removed these presumption, allowing spouses to testify in all circumstances.
The immunity is concern with the state of the relationship at the time of the evidence being given, and not at the time of the incident.
The protection is only only those in a "valid and subsisting" marriage. Thus, the spousal exception does not surived the marriage. "Irreconcilably separated" spouses are not protected where there is no marital harmony to preserve. Thus, spouses with "no reasonable prospect of reconciliation" is exempt from spousal immunity. This is determined objectively and on the balance of probabilities..
A spouse refers only to legally married spouses. Those who are:
- common law,
- separated short of divorce with no hope of reconciliation,
are not subject to the spousal immunity.
A competent spouse for a party is necessarily a compellable witness.
- R v Hawkins,  3 SCR 1043
- R v Hawkins,  3 SCR 1043
- see R v MacPherson (1980) 52 CCC (2d) 547 (NSCA)
R v Czipps (1979) 48 CCC (2d) 166 (ONCA)
R v Sillars (1978) 45 CCC (2d) 283 (BCCA)
- R. v. Schell, 2004 ABCA 143
- R v Lonsdale (1973) 15 CCC (2d) 201 ABCA
- R. v. Salituro,  3 SCR 654
- R. v. Jeffrey, (1993) 84 CCC (3d) 31 (ABCA)
- R. v. Martin, 2009 SKCA 37 This rule was found constitutional at R v Thompson (1994) 90 CCC (3d) 519 (ABCA)
- R v McGuinty, (1986) 27 CCC (3d) 36 (YTCA)
This however is not necessary consistent with UK common law
- R v Zylsatra (1995) 99 CCC (3d) 477
- R v St. Jean (1974) 32 CCC (2d) 438(QCCA)
Other Protected Parties 
An accused person is generally assumed competent and compellable for the defence and not competent for the crown.
A co-accused, charged separately, is a competent and compellable witness for both crown and defence. The only exception is if the only purpose in compelling the co-accused is to incriminate them. The same goes for suspects, charged or uncharged.
A co-accused, charged together, is competent but not compellable by the accused. It is the choice of the co-accused to testify.
A lawyer for an opposing party to an ongoing matter may only be called to testify where the calling party has shown a high degree of materiality and necessity.