And not everyone in a psychiatric hospital is "under the act." Even if they are at risk a lot of people are there of their own volition, so called "voluntary" patients.
It's controversial, as you can imagine, and some people believe we should abandon any form of compulsory treatment.
A recent independent report commissioned by the Human Rights Commission expressed concerns about how solitary confinement and restraint is used when people are detained, and included mental health practices in the report.
It causes a degree of conflict in professionals too: I don't like the idea of compelling anyone into treatment, and yet I've seen lives saved by detaining people against their will, especially if they are at high risk of suicide.
Last year around six per cent of all people seen by Mental Health services were under the act at some point. On any one day 103 people per 100,000 are under "the act", and New Zealand's use of compulsory treatment is one of the highest in the world: around twice that of the UK.
Why would that be so? It seems strangely out of step with our high suicide rate, and mental health services under pressure. Surely it should be decreasing?
But it's the lack of resources that's the problem. Using compulsion is what otherwise caring, client oriented clinicians do when they don't have time to make a connection and form a therapeutic relationship.
Given the huge workload pressure that staff are under, the increases in demand, and the lack of resources - beds, facilities, therapy - locking someone up stops being a measure of last resort, and the only option clinicians have.
So of course we should treat people willingly, and without doubt forcing people to take medication, be in hospital, stay alive, is ethically tricky.
But the only way we can reduce compulsion, is to value relationships, allow time for bonds and connections to be built, and give professionals the space to do what they were trained to do.
Because ultimately it's connections and relationships that makes all our lives worth living.
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Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• Samaritans 0800 726 666
If it is an emergency and you feel like you or someone else is at risk, call 111.