Prof Dawson said New Zealand, compared with the United States, was more willing to restrict people's freedom if they were deemed mentally ill.
In the US, the strong and overriding concept of "negative liberty", or the right to be left alone, was considered sacred, and although it varied state by state, the threshold for compulsion was usually the person posing an imminent danger.
The most common compulsory orders in New Zealand were community-based orders, which were non-existent in the US.
Community-based orders gave authorities the right to enter private property, to recall subjects to hospital and to restrict access to firearms, and they were often imposed indefinitely.
While the concept of negative liberty, or being left alone, was "dear to the hearts of lawyers" the world over, in New Zealand as well as Australia, mental health law had incorporated concepts of freedom that were therapeutic as well as legalistic, Prof Dawson said.
Prof Dawson said he had been shocked to visit the US and find the mentally ill were often homeless and destitute.
"Is the homeless mentally ill person really free?" Mental-health authorities were often faced with dilemmas in New Zealand because of the relatively low threshold for imposing compulsory orders: when people became well, they might want the order lifted, but it was often the compulsory order that had helped them regain their lives and place in the community, Prof Dawson said.
Southern DHB mental health nursing director Heather Casey said the annual nurses' day was a chance for mental-health nurses throughout the region to participate in professional development.
Because of the community setting of mental-health services, many nurses worked in relative isolation from colleagues.
