This paper will examine the collision between Kelsenian and Schmittian ideas in relation to Thailand’s contemporary colour-coded crises. The application of the Kelsen-Schmitt debate in the Thai context exemplifies the declining dominance of the Schmittian idea. Though the “Yellow-shirt” faction in Thai politics is still capable of engineering a military coup—the exercise of sovereign decisionism in the Schmittian sense – such hegemony and ability are declining due to the rise of pro-democracy movements calling for placing political power under the control of a liberal-democratic constitution. Overall, the Thai case reveals the growing need to ‘liberalise’ and ‘institutionalise’ the Schmittian idea, especially by resorting to the Kelsenian legal-technical mechanism, the Constitutional Court. Meanwhile, to move the Kelsenian liberal-democratic project forward, there is also a growing need to resort to Schmitt’s idea of political struggle.