OVM, the study ignored one real reason - the protection from the federal government is going away. States and cities are now enforcing the laws and the constitution that they have an oath to up hold. The states are getting tired of the crime, just last week I think there was a lot of invader activity in Atlanta, oh the money and drugs.
BUT unlike the rather dumb and misinformed people, invaders are at the mercy of the people who they invade. In the case of many of the children and women, they are a commodity and are normally 'sold' into a form of slavery.
The other thing that really gets me is that we are screaming about BIG OIL but we fail to see that other businesses are profiting off the backs of these people who have nothing to begin with. The latest thing has been the Iowa Kosher processing plant where not one person of the company is going to jail for this form of slavery. The plant should become the property of the US government at this point and auctioned off while some of the management of the plant goes off to jail.
As for economics, sorry but we don't need them to be here, it drives our wages down.