It works almost exactly the same way in the united kingdom. The police do a welfare check if they receive a call and if there's evidence and/or two different people (nearest relatives) vouch for the fact that the subject is a danger to themselves, they can get involuntarily sectioned for an emergency 72 hour evaluation period by doctors, then possibly up to one or six months for assessment, at the end of which they can be made to accept treatment.

tl;dr take off your British Indignation hat, anon.