The introduction of FuelEU Maritime and the extension of the EU Emissions Trading System (EU ETS) to maritime shipping mark a significant step toward decarbonizing the sector. However, these regulations may also create unintended consequences, such as cost-driven rerouting and carbon leakage to non-EEA ports. This study investigates the compliance costs and behavioral responses of liner shipping operators through route-based case studies and expert stakeholder interviews. Results indicate that current regulatory designs can incentivize strategic evasive behavior—such as avoiding EEA ports or shifting transshipment hubs—to minimize exposure to EU climate obligations. These strategies risk undermining climate goals and affecting the competitiveness of certain EU ports. To support effective implementation, the study recommends policy measures focused on tightening transshipment rules, improving fuel infrastructure, and aligning EU actions with international frameworks such as the IMO Net-Zero Strategy.