• Privy councils are among the most traditional, yet least conspicuous forms of collective decision-making in modern states. However, using the example of East Asia, this chapter shows that, far from being a moribund relic of the pre-constitutional past, advisory councils to the head of state were a highly productive global element of constitution-building which was variously adapted according to local needs and conditions. The architecture of the Napoleonic Constitution of 22 Frimaire, which complemented the executive ministers of state with an additional Council of State and came to be underpinned by the idea of a “neutral” or “moderating” branch of government, promised attractive advantages to the makers of East Asia’s first modern constitutions. The Japanese Privy Council (Sūmitsuin) alleviated the dangers of putting too much power into the hands of the Emperor, while also securing the power of the ruling oligarchy in a context of mistrust of the legislative branch. The Sūmitsuin served as a model for both the Qing Empire and the Republic of China, although the political objectives attached to the respective advisory councils diverged significantly. Eventually, both in Japan and in China, the institution was abolished when it had become too closely connected with authoritarian politics.