How does the Crown have access to people's mental health diagnoses?

A series of cases occupying the country’s highest courts has cast a spotlight on Crown attempts to probe the personal backgrounds of prospective jurors, potentially undermining the sanctity of the jury system.

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The most contentious case involves a 2007 murder trial in Barrie, Ont., where the Crown was privy to private, background information about the mental health, age and driving records of many of the 280 citizens in the jury pool.  

Important question: how did the Crown come about information about people's mental health? That's medical records.  Does the Crown also know that I have GERD?  Does it know that I had strep throat at xmas?

And here's why everyone should be worried about it, even people who have never sought mental health care: in my experience with mental health care, I didn't just talk to my mental health care provider about the specific issues that are in the DSM.  I also talked to them about my parents' personality traits and my partner's sexual proclivities and the pros and cons of being friends with my friends.  So if mental health information is somehow available to the Crown, any information about your interpersonal relationships with anyone you might know who has sought mental health care should logically be available by the same means.