There will be different responses to this question. I would think that one immediate impact of legalization of prostitution would allow women to be able to demonstrate greater autonomy over their roles in both a social and financial capacity. It seems to me that legalizing prostitution removes the role of the procurer, the middle source, because it is a legal activity. Women might be able to retain more of the profit associated with the profession. Both decriminalization and legalization would allow women a greater opportunity to assert themselves without the need of a procurer who keeps a portion of the woman's earnings. Yet, I think that legalization would be able to remove any stigma from a legal standpoint associated with the act, as indicated previously. I think that this allows a greater propensity for women who work to be able to keep more of the income generated and allow greater choice, as opposed to a system where a women must see her profit making ability decrease because of a lack of legal validation.
The legalization of prostitution would create a recognized profession which would then be regulated and taxed the way that other potentially unhealthy professions are regulated and taxed. Those currently engaged in prostitution have their own level of regulation in place, but because it is not legally enforced and because those involved are essentially performing illegal, cash-based services, the current administration of this profession is based upon the individual power of criminals.
Example: Bonnie, the corner prostitute works for Albert, the pimp. In exchange for an outrageous percentage of Bonnie's earnings, Albert provides her with protection from those who might enjoy her services and then decide not to pay her. Albert is not necessarily a very nice guy, he is a criminal and because he imposes his own "regulation" on his business and his employees, he uses physical violence to prevent Bonnie from embezzling money from the "business". Bonnie receives cash for performing illegal activity; as such she is not paying any taxes. As far as the IRS is concerned, she has no source of income. Bonnie also has none of the benefits that traditionally accompany employment. She is not receiving any credit toward Social Security and if she loses her employment she will not be able to receive unemployment compensation. Finally, Joe, the average joe who hires Bonnie, runs a substantially increased risk of contracting diseases because, although some of Bonnie's co-workers are very health conscious and get regular check-ups, Bonnie herself just doesn’t care that much, and there is no government regulation making it a condition of her employment that she go to the doctor regularly.
Ok, now legalize prostitution and consider the consequences.
Albert is out of a job. Why? Bonnie is now able to go to the police if her clients threaten or abuse her. She can sue them for breach of contract if they don't pay. Therefore Bonnie no longer needs Albert and she can keep the percentage he would take from her. If she WANTS Albert's services, he will have to act as a sort of manager or agent, and he certainly won't be using physical violence against her. Bonnie is also now going to pay income taxes, she will be eligible for unemployment compensation, she will have wages that will build up eligibility for Social Security later in life. And the government will regulate her activities VERY CLOSELY. She will now be forced to have regular doctors visits and STD screenings as part of her profession. As a happy result, Joe, the average joe, will have a markedly lower risk of being exposed to health threats (except, probably, from his wife.)
When considering decriminalization/legalization of prostitution one must consider the impact it would have on females/prostitutes. The change in the laws would mean that it is an accepted behavior and soon laws would be set in place that would require that health codes be followed. For example, the risk of wide-spread sexually transmitted diseases would likely continue in the unmonitored group, but those who moved into houses of prostitution would be more likely to have health checks and follow government regulations in order to stay in operation.
For the street prostitute, the pimps and hustlers who control them would have ca-rte blanch in their industry. The rates of prostitution would increase and more men would purchase prostitute's services. The problem is that prostitutes would still have no protection and still be in danger of harm.