In the wake of the refugee crisis and the global war on terrorism, many European countries are revising their border control strategies. Despite having signed the Schengen Agreement, as a result of which all forms of internal border control within a large section of Europe have been abolished, many countries are exploring the legal possibilities to monitor cross-border mobility. By focusing on the case of the Netherlands, this article aims to assess one of these possibilities: carrying out so-called Schengen proof spot checks in the 20-km zone around the land borders with Belgium and Germany. In this article we aim to examine whether the Dutch Mobile Security Monitor is exercised justly and fairly. We will assess street-level discretionary decision making by officers of the Royal Netherlands Marechaussee, the Dutch border police organization responsible for carrying out the MSM, through the sociolegal lens of the principle of non-misuse of competence also known as détournement de pouvoir . Although the MSM is meant as an instrument of immigration control, based on our extensive qualitative fieldwork this article will show a different picture.