Platform Content Moderation and Freedom of Expression in Southeast Asia: A Systematic Literature Review

Background Big Tech platform self-regulation and national anti-disinformation laws jointly govern political speech in Southeast Asia, a region without a supranational regulatory framework, yet their interaction has not been systematically synthesized. This review examined how they interact in shaping political disinformation and freedom of expression in the region from 2015 to 2025. Methods Following PRISMA 2020, we searched Scopus, ScienceDirect, SAGE Journals, and JSTOR in April–May 2026 for English-language, peer-reviewed studies. Of 3,886 records, 35 studies were included. Quality was appraised with the Mixed Methods Appraisal Tool (MMAT) 2018, and findings were synthesized thematically around three research questions. A large language model assisted screening, summarization, and initial appraisal, with all outputs checked by the authors. The methods were registered retrospectively on the Open Science Framework (doi:10.17605/OSF.IO/BGXHW). Results The studies (2015–2026; 74.3% qualitative) were concentrated in Malaysia and in studies without a single-country focus. Three themes were identified: platform–state interaction (n = 13), regulatory gaps and digital rights safeguards (n = 15), and discursive patterns in platform policies (n = 8). States used legal, technical, and administrative pressure to secure platform compliance, while platforms adapted their moderation largely on pragmatic and commercial grounds. Vaguely defined laws, their misuse, state-linked manipulation, and chilling effects were widely documented, whereas evidence on changes to Terms of Service and on benchmarking against international freedom of expression standards was limited. Platform policy language was strategically ambiguous, and moderation increasingly operated through visibility. Conclusions Ambiguity in both state law and platform policy may function as a feature of governance rather than only as a drafting failure. Improving the governance of online speech in the region is likely to require independent oversight of enforcement, transparency about moderation practice, and co-regulatory arrangements with clearly defined safeguards. Future research should address the underrepresentation of Vietnam, Cambodia, and the Philippines.