The most serious threats to civil aviation include, in particular, aircraft hijackings, bomb attacks, attacks on airport infrastructure, and other forms of interference that could disrupt air transport operations. These phenomena have prompted the development of comprehensive legal regulations at the international and regional levels to ensure uniform security standards. Experiences with terrorist attacks and a growing awareness of the vulnerability of transport infrastructure to threats have largely shaped the evolution of EU legislation on civil aviation security. A particular turning point was the terrorist attacks of 11 September 2001, which led to a significant intensification of legislative activity and the implementation of more restrictive security measures in air transport. This article examines the evolution of European Union legislation in response to terrorist threats. The issue the authors sought to highlight was expressed in the question: What impact did acts of unlawful interference have on the evolution of legislation concerning civil aviation security?