The European parliament has voted overwhelmingly in favour of adopting the so-called Nordic model which legalises the selling of sex, but criminalises buying it.

In 1999 the Swedish government became the first in the world to make it a crime to buy sex but not to sell it.

The ABC's Europe correspondent Mary Gearin travelled to Sweden to witness firsthand how the law had changed lives.

It is a system where buyers of sex are hunted and charged, but prostitutes are free to be sex workers - without penalty.

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The laws are supposed to both protect prostitutes and dismantle their trade.

In theory, Carina Edlund is free to be a sex worker, but she said there was a stigma attached to her job.

"It's such a great part of my life, even though some parts haven't been happy happy joy joy, I'm proud of what I'm doing and it's a part of my life that I'm comfortable with," she said.

Her country is now famous for the system that turned the relationship between prostitution and criminality on its head.

One of the handful of police in Stockholm's prostitution unit, Jonas Henrikksen, draws on his former life in the narcotics unit to track down the clients - mostly men - by monitoring the sex workers.

"We sit here and we watch the buyers approach, and then we filter them out so to speak. We look for different telltales," he said.

He said he makes up to 15 arrests a night by cruising the streets of Stockholm.

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"[In] 99 per cent of the cases the girls tell us exactly how it was, how much the man paid and what they were doing, and usually the man admits as well to the crime; they confess," he said.

"To me, in the beginning, before I understood what the law was all about and what made it so unique, it was a paradox.

"But then I understood that when they wrote the law, they actually managed to implement the fact that men buying sex from women is equal to men's violence against women."

He believes the laws have strengthened links between sex workers and the police.

"If a woman is being used and being in such a bad situation that she has to sell herself to get money, then is it really fair to punish her?"

But Carina tells a very different story. She said the law actually works against sex workers.

"When I meet guys in cars, I've got 20 seconds to feel in my stomach if it's a good client or not," she said.

"So I need to jump in the car and decide if I should get the hell out of the car, or if it's a good client, because the clients want to drive away as soon as possible because they are criminalised."

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A report last month by Sweden's Association for Sexual Education found there was no proof demand had decreased, that prostitutes were facing greater risks, and that they needed to get better support from social services.

Critics of the system said the report showed the laws should be revised.

Marie Johansson counsels both sex workers and clients.

She said the success was measurable not in numbers but in attitude and that the culture around the sex trade had fundamentally changed.

"We don't think its right for someone to be buying another body, another human being, and we still want to show that we don't think it's ok to buy another person, that's it," she said.