Declaratory judgment (DJ) actions, used by alleged infringers as pre-emptive measures to solve trade mark disputes, are still in the development stage in Taiwan. According to our research, up to the end of September 2018, trade mark infringement disputes have generated less than 20 DJs by the Taiwan IP Court since its inception in July 2008. It is against this background that the two trade mark DJs the IP Court recently rendered, both of landmark importance, attracted widespread attention from the local IP community. In the Bullsone decision, the IP Court delineated a two-pronged test for determining whether a prerequisite for filing a trade mark DJ action is met. The Vitalon decision, on the other hand, marks the first win of alleged infringers in DJ actions on the basis of trade mark dissimilarity, and the issue of trade mark owners' burden of proof in DJ actions was also brought to the foreground.