Economic diplomacy, as a strategic tool in foreign policy, is intertwined with international treaty law and creates a bridge between politics and law. This article, with an analytical-comparative approach, examines how states shape international treaties through diplomatic diplomacy to do this in the areas of energy, trade, and investment. Focusing on principles of private international law such as the autonomy of the will of the parties, the rule of law, and protection of foreign investment, it is shown that state economic policies can influence the interpretation and enforcement of contracts, while international legal frameworks such as the 1958 New York Convention and the UNIDROIT Principles place constraints on political intervention. A case study of Iranian oil contracts with foreign companies provides a model of the balance between ensuring national energy security and respecting legal obligations. The results suggest that the successful interaction of politics and law requires efficient dispute resolution mechanisms and proactive policymaking to mitigate geopolitical risks and sustain national interests.