My instinct has always said that transparency should prevail on this kind of issue. However, as it happens, I have previously discussed this exact subject with

My instinct has always said that transparency should prevail on this kind of issue. However, as it happens, I have previously discussed this exact subject with multiple friends who work in clinical healthcare roles, and I have to acknowledge that they have almost invariably disagreed with my instinct. Given that I'm fairly sure some of them have personally treated people with serious mental health problems, I tend to defer to their expertise on this one. I don't know what the law actually is (and perhaps none of us do since as you say the issue doesn't seem to have been tested yet) but if the medical experts are almost universally of the same opinion then I probably know what the law should be.