The objective of this paper is to explore the precariousness of immigrant labour through the concept of ‘deviant policies’. These policies are not explicitly intended to regulate the employment of foreigners, but they lead to the creation of uncertain zones of exploitation and vulnerability for immigrants. To achieve this aim, we conducted an ethnographic investigation of Brazilian immigrants with Irish study visas. The findings of our study indicate that the Irish study visa functions as a deviant policy that gives rise to precarious workers and a network of exploitation that encompasses everything from English language schools to unscrupulous employers.