In institutional settings of globalization, labelled languages are generally preferred over multilingual repertoires and mobile language resources. Drawing on linguistic-ethnographic analysis of the way English is treated as an invariable "ad hoc" idiom in the Belgian asylum interview, this article demonstrates how institutional measures and routines relating to multilingualism fail to address the communicative needs and practices of the participants involved. I argue that by privileging the variety of the host institution as a means to monitor all incoming Englishes, the institution perpetuates traditional--though academically contested--centre-periphery categorizations of global Englishes. I proceed by discussing how the divergent potentialities of the speakers' linguistic repertoires reflect a remarkable inversion of client-gatekeeper resources in the way the participants with the least linguistic resources in the interview process eventually have the power to act as arbiters of what is or is not institutionally relevant for the case.