In 1806, Napoléon Bonaparte convened a synod of French rabbinim (mainly Alsatiens and Bordelais) to ascertain halachic opinions on a set of questions. What is the halachic standing of this synod's decisions and to whom does it apply?
On Wikipedia, the questions are discussed here: http://en.wikipedia.org/wiki/Grand_Sanhedrin#Assembly_of_Notables
According to Rabbi Noson Auerbach, Napoleon's Sanhedrin had no halakhic importance whatsoever. The greatest scholar to be part of the Sanhedrin was R' David Zinsheim, whose works on Shas are edited by R' Noson Auerbach (a descendant of R' Avraham Auerbach, R' Zinsheim's in-law), and in the introduction to one of those works, "Michas Ani" (pg 21-24) he writes that the Sanhedrin was created with the intent of establishing laws that would be favorable to Napoleon, and thus the decisions of the "Sanhedrin" were very much dependent on his acceptance, and Napoleon made sure that the 71 "sages" who made up the synod were both scholars such as R' David but also "Enlightened" Jewish thinkers who would be able to outvote him. R' Noson Auerbach also published this in Yeshurun (2007, pg 995-996).
In the excellent four-volume work, "HaTakkanos B'Yisrael", published by Mossad Harav Kook, there is a small blurb in volume 4 (pg 248) about Napoleon's Sanhedrin, and he likewise states that it served only Napoleon's purpose and shouldn't be considered to have any halakhic importance.
