Selling sex and paying for it are both legal throughout the UK providing it takes place between adult individuals.
But activities like soliciting, controlling prostitutes and kerb crawling are crimes. It is also illegal to pay for sex with a person being forced to comply; even if the buyer doesn't know the seller is acting under compulsion.
Lord Morrow's bill would make it illegal to pay for sex in any circumstances. He believes that this will reduce demand for prostitutes and remove the incentive to traffick women against their will into Northern Ireland.
Similar legislation is in force in Sweden, but was rejected in Scotland. Many European countries have moved in the direction of regulating prostitution and giving prostitutes employment rights.
There is a debate in Sweden about the success of the law. Police believe it would be unhelpful and would prevent men reporting suspicions women were trafficked.
They also believe that, under UK law, the prostitutes would be open to conspiracy charges and would be unlikely to co-operate. The PSNI points out that though there has been a dramatic reduction in street prostitution in Sweden since the sex purchase law was introduced, we have seen a similar reduction here.
There are now fewer than 25 street prostitutes working in Northern Ireland. The fall both here and in Sweden may be down to the internet.
Prostitutes normally pose as "escorts" on websites and then meet clients in hotels or apartments. About 175 people are advertised as escorts here every day. One per cent of cases of suspected human trafficking logged in the UK originate in Northern Ireland – 2.9% of the UK population indicating it is being tackled using existing law.
Police say many trafficked persons are brought here for forced labour, not prostitution, and some work voluntarily, so it is wrong to suggest that trafficking and prostitution are the same thing.
Forced labour has also been detected on illegal cannabis farms, fishing boats, and in restaurant and food facilities.