In Canada, the detention of a foreign national sets in motion a vast network of actors and organizations, including Canada Border Services Agency (CBSA) personnel who play a key role. However, their practice remains seldom studied. This article aims at filling this gap by shedding light on one aspect of this practice, namely the interpretation and application of the legal regime that takes place in the multiple decisions punctuating the detention process. This text is also intended as a “freeze frame shot” of the theoretical and methodological reflection underlying this research. As such, the notions of over-determination and audiences’ expectations are fruitful to understanding the dynamics of the practice of CBSA’s personnel. In return, empirical research conducted with them contributes to a better understanding of the ways in which these expectations are constructed.