The dispute settlement mechanism [DSM] under preferential trade agreements [PTAs] is crucial to ensure adequate implementation and enforcement of commitments among contracting parties. The DSM has evolved from political/diplomatic styles with a low level of legalism to judicial styles with a high level of legalism. Indonesia has also experienced this evolution process in its PTAs. This paper aims to show the evolution of the DSM in Indonesian PTAs, analyzing several related factors behind this trend. The paper argues that the evolution of the DSM from the GATT to WTO, Indonesia's participation in regional trade agreement, that is, ASEAN, the influence of trade partners, the existence of domestic factors, and the ongoing WTO dispute encourage the evolution of the DSM in Indonesian PTAs from political styles to more judicial styles with a high level of legalism.