When the Chinese Revolution led by the Communist Party eventually prevailed in 1949, Zhou Zuoren (1885–1967) wrote to Zhou Enlai—the first premier of the People’s Republic—in the hope of reversing the verdict on his “culpability.” To what extent, Zhou Zuoren asked, was he, a wartime collaborator with the Japanese enemy, recognizable not only as an offender of the traditional moral norms (mingjiao), but also as a traitor of the nation (minzu)? Before the Second Sino-Japanese War broke out, Zhou Zuoren had long been viewed as a leading figure of the Chinese “New Culture.” Zhou Zhuoren’s sudden decision to collaborate with the Japanese Occupation in 1938 then turned out to be a traumatic and scandalous event for the Chinese intellectual community. The whole case of his collaboration exposed, in disturbing ways, the convergences and the divergences of law, morality and politics in China’s modern nation building. By revisiting this controversial case, this paper attempts at a symptomatic reading of the following texts: “An Open Letter to Zhou Zuoren” written collectively by a group of Chinese intellectuals, court documents of the post-war trials, and Zhou Zuoren’s letter to Zhou Enlai. This re-reading focuses on the domain of the cultural-political rhetoric, within which Zhou’s contentious “culpability” has turned into an ambiguous zone of modern law, traditional morality, and nationalism in East Asia.