In the criminal case of R v Nguyen (Ont CA, 2015) the Court of Appeal commented on several basic principles of evidence law while considering whether the spousal incompetency rule (that spouses are not competent to testify against spouses) should be extended to common law spouses by virtue of the s.15 equality provisions of the Charter.
On compellability the court stated:
 A compellable witness, on the other hand, is “one who may be forced by means of a subpoena to give evidence in court under the threat of contempt proceedings”: R. v. Darrach, 2000 SCC 46 (CanLII),  2 S.C.R. 443, at para. 48 (citations omitted).
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