This Thesis comparing the legal systems of different models, such as Iraq's state organization for selling oil, Hungarian Mol company, US Exxon Mobil, and Saudi Aramco, this thesis aims to provide a comprehensive understanding of the challenges and opportunities faced by oil marketing companies in the current energy transition. Through a detailed analysis of the historical, structural, functional, and regulatory aspects of the selling process, this thesis offers insights into the complex and dynamic nature of the oil industry's legal landscape.