Irregular migration has posed a persistent challenge to the European Union for decades, reaching a critical peak during the 2015–2016 migration crisis. In response, several Member States implemented physical border protection measures, including the construction of fences and barriers. This study investigates three core research questions: (1) whether the erection of border fences represents a unique phenomenon in Europe; (2) whether such measures are lawful under EU border protection law; and (3) whether they are effective in mitigating irregular migration. Drawing on time-series data from FRONTEX (2014–2025), the paper analyses trends in irregular border crossings and the evolution of physical border infrastructure across the EU. The findings indicate that border fences are not unprecedented in Europe, are legally permissible under current EU frameworks, and can serve as a legitimate, though not exclusive, tool for managing migratory flows. The study also explores conceptual distinctions between irregular and illegal migration and considers the instrumentalization of migration as a political tactic. While physical barriers may reduce pressure on specific border sections, their effectiveness is contingent upon broader geopolitical, legal, and humanitarian factors.