Courts are becoming major players in the political landscape of Southeast Asia. This paper seeks to examine the causes and consequences of this new trend with particular reference to Thailand. Our study primarily analyzes the behavior of the Thai Constitutional Court during the political crisis in 2006-2008; the findings suggest that recent judicial activism and assertiveness in political matters, while partly explained by the interests of judges themselves and by the constitutional rules guiding their activities, is best understood as a direct consequence of the intervention of the monarchy, to which the judiciary has traditionally been closely aligned. Accordingly, the Thai case not only provides new evidence about what may be driving the new judicialization trend, it also draws attention to problematic aspects of this trend, namely the gradual politicization of the Thai judiciary and with it the erosion of the rule of law in Thailand and its replacement with rule by law. Our findings may also illuminate some larger issues at the intersection of politics and the courts throughout the region in ways that advance the theoretical understanding of both.