Toronto area family law attorney John P. Schuman was recently asked the following question: “I came home to notice my wife was recording/spying on me with her laptop though she wasn't around. I was able to notice because the webcam light was on. Is this a crime?”
Yes. Intercepting any form of conversation, to which you are not a party is a breach of section 184 of the Criminal Code of Canada and possibly other sections, depending on what your ex records.
And, recording conversations usually will not help you in family court. While it may not be one of the top 10 biggest family court mistakes, breaking the law will not make a judge like your ex. In addition, except in extreme circumstances where the evidence is necessary to protect a child from harm, illegally obtained evidence is not admissible. Judges only pay attention to admissible evidence, so even if your ex does record something that she thinks helps her case, chances are the judge will not even look at (or listen to) it.
Judges also really hate it when one parent tries to interfere with the other parent's time with the children, or even worse, tries to prevent the children from having a relationship with the other parent. If your ex was trying to record your time with the kids, that will come off really badly - the only worse thing your ex could do would be to "interview" the kids about the child custody issues and record that conversation. No good comes from putting your kids in the middle in Family Court.
Chances are, unless your are a lawyer, you will not know the Rules of Evidence, or the specifics of the Criminal Code. That is why it is good to get legal advice for your specific situation.