It's certainly true that vulnerable adults need to be protected from forced prostitution, however is it not terribly demeaning to all of the 'career' prostitutes of which there are many, the majority even, to have their rights to live and work as they wish curtailed by what is in effect state interference in their lives?
I'm very in favour of prostitution being in all it's forms as transparant and safe as possible for the ladies that work in the industry as I believe that that is not only morally right, but also the best way to tackle the exploitaiton of those at risk. Sadly you will never stamp out traffiking completely or forced prostitution, as life always has it's unfortunate victims, but I think the more open the industry is the safer it is for most concerned and this legislaiton will in effect cause a greater stigma in relation to prostitution in general and thereore cause more trouble than it's worth and possibly make things even worse for those that are traffiked.
You might want to take a look at the ' all women count' website, run by sex workers for sex workers for a really informed view on what they think of things.
http://www.allwomencount.net/EWC%20Sex%20Worke rs/SexWorkIndex.htm