The Justice Committee of the Scottish Parliament is right to endorse the Scottish Government's proposed human trafficking legislation.

The Human Trafficking and Exploitation (Scotland) Bill, introduced to parliament last year, will create a specific offence of human trafficking for the first time.

It will increase the maximum penalty for people traffickers to life imprisonment and help victims by introducing a presumption that they will not be prosecuted for crimes they are forced to commit by others.

Overall it represents a welcome strengthening of Scotland's response to human trafficking and modern day slavery, by making it a matter of criminal law.

However some wanted the bill to go further. A significant campaign has been fought suggesting the committee should urge ministers to revise the bill to criminalise the purchase of sex.

There is a precedent for this, as a similar trafficking bill in Northern Ireland was used to change the law in this way, and buying sex there is now illegal.

But the Justice Committee has chosen not to support such an addition to the bill and it is right to do so. While members urge cabinet secretary Michael Matheson to meet with those on both sides of the debate before the bill is finalised, the committee says the bill is not the right vehicle for changing this aspect of the law.

There is a strong argument that addressing demand, by addressing the men who (predominantly) purchase sex is the only way effective way to tackle prostitution. There is undoubtedly a crossover between the trafficking of women and children and exploitation for sex and the sale of sex.

However conflating the two issues is questionable and unlikely to be helpful.

It is true that most prostitutes in Scotland now are foreign. But it is not clear how many are coerced, or trafficked. Just 99 people were referred by agencies in Scotland as potential victims of trafficking in 2013, yet Police believe around 3,000 woman are sex workers.

They are not all undetected victims of trafficking. Neither is all human trafficking about sex.

Meanwhile, the Scottish Parliament has only recently debated the issue of criminalising the purchase of sex, through the bill introduced by Rhoda Grant in 2013.

Revisiting this debate via the back door in this way could delay the other important measures in this bill.

These include safeguards against the prosecution of victims - at present there is still a danger that many victims of human trafficking swept into the criminal justice system in the guise of 'saving' them.

Meanwhile the criminalisation of the purchase of sex, while superficially an attractive policy, is a complex issue. There has been insufficient time to assess the effect the change to the law has had in Northern Ireland and debate about the impact of criminalisation in Sweden.

It is important the law is strengthened, to protect victims of trafficking from coercion and exploitation and to bring their traffickers to justice.

We may also wish to revisit the issue of criminalising buyers of sex and debate whether this would protect sex workers. But the Justice Committee is right to conclude that these two issues are best kept separate.