The number of sex workers in New Zealand does not appear to have increased since legislation decriminalising prostitution became law, according to a new report.
The Prostitution Law Review Committee was set up to report on the Prostitution Reform Act 2003 three to five years after the act came into force.
Its report, just published, was based on work carried out by the Christchurch School of Medicine and Victoria University's Crime and Justice Research Centre.
The committee, chaired by former Police Assistant Commissioner Paul Fitzharris, said an accurate count of the number of sex workers was difficult.
However, a comparison between the number of sex workers in Christchurch in 1999, before decriminalisation, and 2006 - after the act was passed - showed the total had stayed about the same.
A 2007 estimate in five centres - Auckland, Wellington, Christchurch, Hawkes Bay and Nelson - found a total of 2332 sex workers, the committee said.
Numbers of sex workers should continue to be monitored, it said.
Around 93 per cent of sex workers cited money as the reason for getting into and staying in the sex industry.
"The most significant barriers to exiting are loss of income, reluctance to lose the flexible working hours available in the sex industry and the camaraderie and sense of belonging that some sex workers describe."
The committee said a Christchurch School of Medicine survey found that more than 90 per cent felt they had legal rights under the act.
More than 60 per cent felt they were more able to refuse to provide commercial sexual services to a particular client since the enactment of the law.
Before the act, the illicit status of the industry meant workers were open to coercion and exploitation by managers, pimps and clients. Research indicated there had been "some improvement" in employment conditions "but this is by no means universal".
Generally, brothels that had treated their workers fairly before the act continued to do so, while those that did not, continued to have unfair management practices, it said.
"The committee recommends that the sex industry, with the help of the Department of Labour and others, moves towards written, best-practice employment contracts ... becoming standard for sex workers working in brothels."
Other findings included that the majority of sex workers felt the act could do little about violence that occurred, although a significant majority felt there had been an improvement since the passing of the act.
The legislation made it an offence to arrange for or to receive, or facilitate or receive payment for, commercial sexual services from a person under 18.
The committee said the threshold of 18 should remain.
It found 1.3 per cent of sex workers were under age but did not believe the act had resulted in more underage people working in the industry.
Other recommendations included that the Government provide additional funding to the Ministry of Health to enable medical officers of health to carry out regular inspections of brothels.
It also said the Government should provide funding so that non-government organisations could provide services, including assistance with exiting for those who wanted to quit sex work.
Associate Justice Minister Lianne Dalziel said the report showed the act had had a positive effect on the health and safety of sex workers and had not led to an increase in numbers of sex workers as predicted by critics of the law reform.