Spousal immunity is a principle of the common law which says that married spouses can't be forced to testify against each other in criminal proceedings, and is intended to protect and promote trusting spousal relationships. This principle has been overruled to some extent by s. 4 of the Canada Evidence Act, the legislation that applies in criminal proceedings. Under this section the Crown can require spouses to testify for the purposes of certain, specified offences, but otherwise:
"No husband is compellable to disclose any communication made to him by his wife during their marriage, and no wife is compellable to disclose any communication made to her by her husband during their marriage."You can see the problem. The immunity provided by the Canada Evidence Act and the common law rule applies only to "husbands" and "wives," and unmarried couples, regardless of how long they've lived together aren't "husbands" or "wives." As a result, the court had to decide firstly whether the nature of the couple's relationship was "common law" and, if so, whether the common law rule which prohibits the Crown from requiring accused person's spouses from giving evidence should apply to people in unmarried, "common law" relationships.
(I will pause here to again say that the term "common law marriage" in the context of these relationships is incorrect and misleading. There was such a thing once upon a time a couple could be legally married, without marriage licences from the state or the blessing of a priest, by meeting in public before witnesses and promising to live together and be faithful to one another but various Marriage Acts have long since repealed this form of marriage. Although the federal government persists in using the term "common-law partner" in its legislation, there is no such thing under the law. In fact, most of the time what matters is whether a couple fits a particular law's definition of "spouse," which makes the status of a relationship a statutory issue not a common law issue. The Family Law Act, for example, defines "spouse" as including married couples as well as couples who have lived together in a marriage-like relationship for at least two years.)
Thankfully, there are a boatload of cases that cover the issue of whether a particular romantic relationship is spousal or not in the absence of a legal marriage. The court drew from an old Supreme Court of Canada case about unmarried spouse's entitlement to statutory benefits to describe the factors that tend to show that a particular relationship is a spousal ("common law") relationship:
- whether or not the persons have a conjugal relationship;
- the degree of exclusivity of the relationship;
- the conduct and habits of the persons in respect of household activities and living arrangements;
- the degree to which the persons hold themselves out to others as an economic and domestic unity;
- the degree to which the persons formalize their legal obligations, intentions and responsibilities toward one another;
- the extent to which direct and indirect contributions have been made by either person to the other or to their mutual well-being;
- the degree of financial dependence or interdependence and any arrangements for financial support between the persons;
- the care and support of children; and,
- the ownership, use and acquisition of property.
" ... I find that the common-law rule is inconsistent with modern Charter values and an appropriate remedy would be to extend the non-compellability aspect of this to common-law couples. In doing so, I am persuaded by the analysis of the Alberta Court of Appeal in [R. v Legge] on the issue of interpreting the common-law in a manner consistent with the Charter. Paperny J.A. on behalf of the unanimous court wrote:
 Canadian courts have long applied and developed common law principles in a manner consistent with the values enshrined in the Charter ...
 In [R. v Salituro], Iacobucci J. commented on the development of the common-law to comply with Charter values in the context of an exception to the spousal immunity rule (at para 37):
These cases reflect the flexible approach that this court has taken to the development of the common law. Judges can and should adapt the common law to reflect the changing social, moral and economic fabric of the country. Judges should not be quick to perpetuate rules whose social foundation has long since disappeared. Nonetheless, there are significant constraints on the power of the judiciary to change the law. As McLachlin J. indicated in Watkins, in a constitutional democracy such as ours it is the legislature and not the courts which has the major responsibility for law reform; and for any changes to the law which may have complex ramifications, however necessary or desirable such changes may be, they should be left to the legislature. The judiciary should confine itself to those incremental changes which are necessary to keep the common law in step with the dynamic and evolving fabric of our society. At paras 48-49 he went on to say:
The Charter has played and will continue to pay a central role in defining the legal and social fabric of this country. As the Charter is the supreme law of Canada, any legislation or government action or law inconsistent with it is, to the extent of the inconsistency, of no force or effect. But the Charter will also be influential even in the absence of legislation or government action... Where the principles underlying a common law rule are out of step with the values enshrined in the Charter, the courts should scrutinize the rule closely. If it is possible to change the common law rule so as to make it consistent with Charter values, without upsetting the proper balance between judicial and legislative action that I have referred to above, then the rule ought to be changed...
" I find the analysis of Paperny J.A. apt in the particular circumstances of this case. [The partner] and the Defendant are in a committed, long term relationship akin to marriage. The Supreme Court has taken note of changing societal values regarding common-law partnerships and the importance of recognizing and protecting relationships that are functionally equivalent to marriage. I find that it is both just and appropriate to extend the immunity rule to make common-law spouses in committed relationships akin to marriage non-compellable witnesses for the Crown. Put differently, [the partner] cannot be compelled to testify for the prosecution in this case, but I make no finding with respect to her compellability at the request of the Defence. ...
" Having considered the narrow issue before me and the corresponding authorities on point ... I find that an appropriate remedy would be a common-law remedy which addresses the current nature of the common-law rule as it pertains to common-law couples. These reasons do not purport to read in language to the [Canada Evidence Act] or expand the definition of husband and wife to include common-law spouses as envisioned by s. 4 of the [Canada Evidence Act]. ..."And there you go. The courts of Canada can and should use Charter values to adapt the principles of the common law where the rationale underlying the common law is inconsistent with the Charter, and in this case the result was the extension of the common law principle of spousal immunity to unmarried ("common law") spouses.