Canadian court rules on scrapped ‘spousal incompetency’ principle

R v Nguyen, 2015 ONCA 278 (24 April 2015)

In R v Nguyen, the Court of Appeal for Ontario held that a rule which rendered spouses incompetent to testify against each other ("the spousal incompetency rule"), was discriminatory against unmarried couples (referred to as "common-law spouses" throughout the judgment). However, the Court declined to extend the rule on the basis that it was inconsistent with individual autonomy, dignity and self-worth.

The case involved an appeal by three men who had been convicted of serious criminal offences. At trial, the common-law spouses of two of the men gave evidence for the Crown. All three men appealed on the basis that the trial judge erred by failing to extend the spousal incompetency rule to common-law spouses. The appellants submitted that the narrow operation of the rule amounted to discrimination on the basis of marital status, in breach of section 15(1) of the Canadian Charter of Rights and Freedoms.

The spousal incompetency rule has long been controversial, and a bill to repeal it entirely was before the Canadian legislature at the time of this appeal. The day before the judgment was handed down, the Canada Evidence Act was amended to provide, in section 4(2), that "no person is incompetent or uncompellable to testify for the prosecution by reason only that they are married to the accused."


On 5 October 2002, Quang Thi Nguyen ("Quang"), a drug dealer, was shot and killed in a karaoke bar by a white male, who has never been identified. At the time of his death, Quang owed money to one of the appellants, Bao Quoc Nguyen ("Bao"). Bao and Quang had met at the karaoke bar to discussrepayment of the debt. One of Bao's associates, Kien Binh Tu ("Binh") was also present at the bar, and had been drinking and chatting with the unidentified shooter earlier that evening. Bao's brother, Bao Tri Nguyen ("Tri") later helped Binh to flee to Vietnam, where he remained for almost four years. After he returned to Canada, all three men were arrested. The Crown alleged that Bao and Binh orchestrated the execution-style murder.

At trial, Bao's common-law spouse, Quynh Ngo ("Quynh"), gave evidence for the Crown concerning some basic matters, but was declared an adverse witness after answering "I can't remember" more than 100 times. Binh's common-law spouse, Caroline Tran Minh, also gave evidence for the Crown, in which she denied that she had helped Binh to hide from the police.

The trial judge also admitted out-of-court statements made by Quynh to another woman at the karaoke bar shortly after Quang was shot. Effectively, Quynh had said that Bao was upset with Quang; that Bao had spoken to Quang earlier in the day; and that Bao had arranged to meet Quang at the karaoke bar.

Bao and Binh were convicted of first degree murder. Tri was convicted as an accessory after the fact. All three men appealed. They submitted that the spousal incompetency rule should have applied, so that the testimony and the out-of-court statements of their common-law spouses would have been inadmissible.


Justice Gillese (with whom Justice van Rensburg agreed) found that limiting the spousal incompetency rule to married couples does discriminate against unmarried couples. Such discrimination is contrary to section 15(1) of the Charter. However, Her Honour nevertheless declined to extend the spousal incompetency rule to common-law spouses, on the basis that the limited application of the rule was "demonstrably justified" in accordance with section 1 of the Charter.

Justice Gillese acknowledged that the rule was based on social, cultural and moral concerns, including a desire to protect "marital harmony" and avoid "the natural repugnance resulting from one spouse testifying against the other". However, Her Honour also noted that the rule was inconsistent with the general presumption that a person is competent to testify. The rule also departed from the notion that all relevant evidence should be placed before the court. Perhaps most importantly, Her Honour found that the rule restricted a spouse's dignity and autonomy by rendering them incompetent to testify, even if they wished to do so. Ultimately, Her Honour concluded that any extension of the rule was a matter for the legislature.

The third member of the court, Justice Weiler, substantially agreed with the majority. However, Her Honour went further and found that, even if the spousal incompetency rule were to be extended to common-law spouses, the other evidence in the trial was so overwhelming that a finding of guilt was inevitable.


R v Nguyen deals with a difficult issue in an unusual political context which is unlikely to be repeated. This decision is an important example of the balancing act courts must perform when determining whether the principle of non-discrimination justifies the extension of anachronistic, gendered rules to non-marriage relationships.

The spousal incompetency rule is thought to originate either from the biblical notion that spouses are "one flesh", or the historical duty of obedience owed by a wife to her husband. There is no longer any equivalent provision in Australian law, following the High Court's decision in Australian Crime Commission v Stoddart (2011) 244 CLR 554. When R v Nguyen was heard, however, the spousal incompetency rule was still enshrined in Canadian legislation, and the validity or interpretation of that statute was not an issue before the Court. As a result, the Court had little scope to critique the rule.

Although this particular issue now appears to have been rectified in Canadian law, R v Nguyen provides essential guidance for practitioners working on discrimination matters where the particular privilege sought is of dubious value to society, or is itself contrary to other human rights. Justice Gillese finds a delicate balance between, on the one hand, the need to avoid discriminating against unmarried couples, and on the other, the need to confine the application of a rule which deprives individuals of the "individual autonomy and human dignity associated with testimonial competence". Although it may seem artificial or discriminatory to distinguish between marriage and other intimate relationships in this way, the Court was justified in restricting the operation of the spousal incompetency rule as much as possible because of its detrimental impact on other significant rights and freedoms.

The full text of the decision can be found here.

Philip Marquet is a law graduate at Allens