The invariance of the speed of light in vacuum is a foundational element of specialrelativity and a cornerstone of modern physics. While this principle has been confirmedacross a wide range of experiments, it remains of interest to examine whether the light-speed limit constitutes a fundamental constraint or an emergent feature of relativistickinematics. In this work, we analyze the origin of the light-speed barrier within the rel-ativistic energy–momentum framework and explore the possibility that this limit arisesfrom the specific form of the dispersion relation. We consider phenomenological modifi-cations to high-energy kinematics that preserve causality, conserve energy–momentum,and recover standard special relativity in the low-energy regime. Implications for wave–particle duality are examined, and potential observational consequences are identified.