Plastics pollution is a global planetary threat to both humans and the environment, leading to injustice throughout its lifecycle and disproportionately affecting the most vulnerable. The United Nations Environmental Assembly adopted Resolution 5/14 to create a legally binding instrument to end plastics pollution, known colloquially as the Plastics Treaty. The treaty is currently under negotiation, and the implicit understandings of justice that will be incorporated will significantly impact the outcome of the treaty. This thesis employs critical discourse analysis and key stakeholder interviews to examine the various justice narratives and framings of actors in the treaty through an environmental justice lens. Additionally, the role of power in shaping these narratives is examined from a critical and decolonial perspective. My research demonstrates the value of a critical approach in addressing power dynamics and normative concepts such as justice in social-ecological and sustainability research. This study identifies three distinct discourses, each offering different problematizations of plastics and justice framings. The analysis reveals competing definitions of just transition, a disconnect between the recognition of Indigenous Knowledge and the rights of Indigenous People, and underdeveloped gender and intersectional considerations. Furthermore, this thesis highlights the enduring influence of colonial dynamics on plastics pollution, potentially reinforcing waste colonial relations in the Plastics Treaty. Finally, this thesis contends that problematizing plastics as a human rights issue offers a valuable approach to address these shortcomings, thereby enhancing the treaty's potential for promoting justice by ensuring that the voices of those most affected are heard.