This contribution analyses if and under what conditions bottom-up pressures constrain the Court of Justice of the European Union (CJEU). Neofunctionalists famously explained the power of the Court by its use of ‘law as a mask and shield’. Due to its technical nature, the Court is able to mask the political substance of ‘integration through law’ and to shield it from political challenges. We revisit this argument in times of politicization of the EU and develop a typology of four constellations depending on different kinds of bottom-up pressures. We argue that depoliticized integration through law still functions, to varying degrees, in face of either governmental contestation or public politicization. By contrast, if member state governments and the public jointly oppose further integration through law, the Court is constrained as further expansive jurisprudence could even reinforce politicization and risk political backlash. We illustrate our argument with case law on EU citizenship.