The US initiated a Section 301 investigation against China in 2017. Such a unilateral investigation has run counter to the explicit commitments in the Statement of Administrative Action. Even the basically reasonable ‘four corners’ defense can neither apply nor justify this investigation. Consequently, especially based on the Panel’s additional emphasis, the conditional international legality confirmed by the Panel of DS152 case in the WTO should be untenable in this latest specific context. By reutilizing this globally aversive tool, the United States could possibly prove itself to be an unreliable partner and this would unavoidably incur severe reputational costs and other potential harms to itself. Furthermore, this might, to some degree, undermine or even undo the advances achieved in more than twenty years of international rule of law in world trade after the establishment of the WTO. All in all, only mutually beneficial solutions are most desirable, effective and sustainable for both China and the US.