In Alberta, for example, the Mental Health Act is what we use to give broad authority to arrest someone who poses a risk, so it's likely—that “likely” isn't there, but in this language it would have to be there—that they pose a risk to themselves or to others. The language, I think, in most mental health acts is along those lines: they pose a risk to themselves or others.
On June 14th, 2018. See this statement in context.