Citizens can play an integral role in protecting the environment and upholding the integrity of environmental laws. In many countries, governments are giving citizens and nongovernment organizations more power to bring environmental litigation against both the government and private parties to protect the public’s interest in a healthy environment. This briefing report focuses on environmental public interest litigation as a potentially transformative mechanism that can empower communities across Southeast Asia to play a significant role in ensuring that environmental laws are complied with, and that the precious ecosystems of the region and the communities that depend on them are protected. The report provides an overview of the various forms of environmental public interest litigation, including an overview of some of the recent progress on burgeoning environmental public interest litigation systems in Southeast Asia. The report reviews some of the prospects and ongoing challenges concerning strengthening environmental public interest litigation in the region. The report finds that a functioning system of environmental public interest litigation would help to reinforce the right to a healthy environment, as recognized in the landmark resolution adopted by the United Nations General Assembly in July 2022 and reinforce widely recognized environmental rights principles related to access to information, public participation and access to justice.