Initially, international investment law and international law on the protection of the marine environment were two branches that developed separately. As these international regimes mature, they often speak to the same facts, bringing about their ever-increasing normative interaction, way before any disputes arise. The regulation of investments in offshore energy production is chosen as a case study because it exemplifies how these two bodies of international law can interact. The article does not conceptualize these two international regimes as inherently antagonistic but instead highlights their potential complementarity. Yet, it is primarily the issue of normative conflicts between those two regimes which has generated heated scholarly debates. Against the backdrop of sweeping critiques about the potential ‘regulatory chill’ of international investment agreements and their investor-State dispute settlement mechanism, this contribution examines whether arbitral tribunals have interpreted and applied investment rules in a fashion that can unduly restrict the discretion of host States to honour their marine environmental obligations. First, it explores why and how international investment law and marine environmental law interact and influence each other’s implementation. In a second step, the article investigates the impact (if any) of investment obligations on the discretion of host States to comply with their marine environmental protection obligations. Adopting a forward-looking perspective, it finally enquires into the potential impact of the reformed provisions under new generation IIAs on the right and duty of States to take all necessary measures to protect the marine environment against pollution from offshore energy production activities.

最初，国际投资法和保护海洋环境的国际法是分开发展的两个分支。随着这些国际制度的成熟，它们经常以相同的事实说话，从而在任何争端出现之前就实现了不断增加的规范互动。选择离岸能源生产投资的监管作为案例研究，因为它举例说明了这两个国际法体系如何相互作用。本文并未将这两种国际制度概念化为内在的对立，而是强调了它们潜在的互补性。然而，引起学术争论的主要是这两种制度之间的规范冲突问题。在广泛批评国际投资协定及其投资者与国家争端解决机制的潜在“监管寒意”的背景下，本文探讨了仲裁庭是否以可能过度限制东道国自由裁量权的方式解释和应用投资规则履行海洋环境义务。首先，它探讨了国际投资法和海洋环境法为何以及如何相互作用并影响彼此的实施。在第二步中，本文调查了投资义务对东道国履行其海洋环境保护义务的自由裁量权的影响（如果有的话）。以前瞻性的眼光，