Published in Proceedings of the National Academy of Sciences, the study tried to identify how migrants are likely to move from one country to another, based on different levels of restriction. Under this, there were three kind of visas: high-skilled visas, low-skilled and family visas.
According to the report, restricting students and those eligible for high-skilled visas, does not significantly change the numbers of incoming migrants. When family and low-skilled visas are restricted, there is a reduction in migration, but this leads many migrants towards unauthorised channels.
In addition, under a scenario where anyone could migrate as long as they comply with minimal visa eligibility requirements, only 44% of aspiring migrants chose to move through legal channels.
What is more, when restricting low-skilled worker or family migration,immigration was reduced by 21% and 32% respectively. However, unauthorised immigration was increased by 14% and 24%.
These results indicate that enforcing unauthorised migration is not an efficient solution as more than 80% of unauthorised migrants would need to be apprehended to balance the effects of legal restrictions.