So rarely is light shed on the dark side of Australia's sex industry that some in the industry would have us believe it doesn't exist. But every now and then the industry's ugly underbelly is exposed, and so it was when former Tasmanian MP Terry Martin was arrested in 2009.
Martin protested that he believed the prostitute he had paid for sex was 18 years of age. She was, in fact, a 12-year-old child.
It emerged, to widespread disgust, that the girl's mother and a pimp had sold her into prostitution with more than 100 men.
Martin was charged, and found guilty in December of unlawful sexual intercourse with a person under 17 and of producing child exploitation material, after taking photographs of the girl posing.
But Martin escaped jail time, despite being found guilty of procuring a pre-teen girl for sex, after the judge accepted his defence that Parkinson's disease medication had given him ''hypersexual desire''.
Martin was the only one of the men prosecuted for sleeping with the child, because he had paid more to have her visit him at his home for sex; the other men had paid to sleep with the child at her stepfather's flat.
The question of consent between women selling sex and their male clients is a contentious one. It is one on which opponents and supporters of the industry will never agree. But there is little doubt that in the case of the 12-year-old girl sold into sex work, and women and girls who are forced to work in the industry against their will, consent is not an option. It cannot be given.
Superintendent Glyn Lewis is the national coordinator of the Australian Federal Police's human trafficking team, based in Canberra. Lewis is a measured policeman of more than 20 years' experience who is responsible for offices in Melbourne, Sydney and Brisbane.
Lewis says that since January 2004, the taskforce has investigated 320 cases and identified and referred 207 suspected victims. Most were from Thailand, but in recent years the number of Thai nationals being trafficked has fallen, while the number of South Koreans has risen.
Sex trafficking attracts more public recognition than it used to, but Lewis says it is a crime difficult to identify and prosecute.
''It's a victim-oriented crime,'' he says. ''These are serious offences; it's 25 years' imprisonment, so it's a very serious offence. You've got victims possibly in a brothel and required to perform sex acts several times a day and being forced to do that ... We're dealing with people that are often suffering from fairly heinous crimes. And that brings its complexities.''
One of those complexities is the difficulties in corroborating victims' stories, when language is an issue or they are living in fear of speaking out.
Some sex workers believe the prevalence of sex trafficking is overstated by activists who oppose prostitution on moral grounds, and will not believe women choose to enter the field willingly. One told The Canberra Times she suspected young Asian women claimed they had been trafficked only when their immigration status was discovered, to ''save face'' and avoid their families' being shamed by their work.
Lewis is reluctant to give this view much oxygen.
''We treat every matter individually and it is a victim-oriented crime so I couldn't comment on that,'' he says. ''Every one of those victims has their own story ... we treat each and every one of them as a victim of trafficking even when there's a chance they're not.''
No one has yet been prosecuted for sex trafficking in the ACT, but Lewis says one case may come close.
In October 2009, AFP officers charged a Canberra-based woman with possessing a slave, debt bondage, attempting to pervert the course of justice, allowing non-citizens to work in breach of visa conditions, allowing unlawful non-citizens to work and operating an illegal brothel.
The charges were laid after a Thai-born woman alleged she had been recruited by the woman to work in Australia and had been forced to sleep with clients to pay off a $43,000 ''debt''.
That case is now before the courts.
Lewis is reluctant to comment on that particular case but says in general terms that debt bondage is a significant feature of sexual servitude. Debt bondage typically occurs when a worker is recruited from interstate, or overseas, to work - only to find on their arrival that they have accrued a ''debt'', typically between $40,000-$50,000, they must repay.
''It's about someone not having the freedom of movement,'' Lewis says. ''And part of that coercion might be that you're debt-bonded.''
Morals campaigners have told an ACT Legislative Assembly committee reviewing the territory's sex laws that legal prostitution can encourage sexual slavery and violence against women.
Melinda Tankard-Reist told the committee the ACT Government was ''complicit'' in sexual violence against women when it accepted licence fees for brothels.
The Coalition Against Trafficking in Women Australia took a similarly hardline view.
It recommended the ''criminalisation of buyers of prostituted people, and people who organise the prostitution of others, decriminalisation of prostituted people as victims of crime, and the establishment of services and facilities to assist them''.
It also sought a public education campaign to recast prostitution ''as a human rights violation''.
Project Respect, the feminist organisation started in Melbourne to counter the sexual exploitation of trafficked women, takes a hardline view of sex work, describing it as ''sexual exploitation''.
''Why do women stay in prostitution?'' its website asks.
''Intimidation, fear, psychological and physical violence.''
Whatever one's view of sex work, Lewis says sexual slavery is an invidious offence that deserves serious attention.