The Architecture of ASEAN’s External Free Trade Agreements: A Textual Similarity Analysis

As the Association of Southeast Asian Nations (ASEAN) and its member states have expanded their regional, plurilateral, and bilateral trade agreements, they have developed one of the world’s most densely interconnected FTA networks. This overlapping architecture raises questions about where ASEAN’s external FTAs converge around recurring textual models and where they remain fragmented. This paper applies a quantitative text-as-data approach to 65 FTAs across 12 substantive chapters. Using character 5-gram Jaccard similarity, hierarchical clustering, largest-cluster-share analysis, and party-level measures of internal and external similarity, it maps patterns of textual proximity and clustering.

The findings show that convergence is highly uneven across policy areas. Trade in services, investment, rules of origin, and trade remedies display relatively high similarity and form broad clusters at comparatively strict distance thresholds, a pattern consistent with established drafting structures and earlier treaty models. Trade in goods, customs procedures, sanitary and phytosanitary measures, and technical barriers to trade show intermediate convergence: detailed wording varies, but clusters expand rapidly as the threshold is relaxed, suggesting shared institutional frameworks and basic chapter structures. Competition, electronic commerce, intellectual property, and government procurement exhibit weaker or more uneven convergence, with field-specific configurations rather than a single common pattern.

Cluster analysis also identifies recurring partner-centred groupings, most pronounced for Japan and the United Arab Emirates, alongside more limited ASEAN-centred and mega-regional clustering. Party-level analysis further shows that Japan and the European Union combine relatively high internal similarity with relatively low external similarity, indicating coherent but comparatively distinctive treaty language. ASEAN, treated as a collective contracting party, lies near the sample means, consistent with the common structure of ASEAN+1 FTAs and their proximity to broader regional treaty practice.

Overall, ASEAN’s external FTA architecture is layered rather than homogeneous. Broad convergence coexists with localised and party-specific patterns of clustering and fragmentation, while textual similarity alone does not establish substantive legal equivalence or the direction of treaty influence.