The proposed California wealth tax has galvanized a host of billionaires who have lined up to fight it. On the other side lies a group of less obvious power brokers: the four professors who drafted the ballot measure. The group is made up of three professors at the University of California: Berkeley economist Emmanuel Saez and law professors Brian Galle and Darien Shanske, at Berkeley and Davis, respectively. The fourth is tax scholar David Gamage at the University of Missouri’s law school. The four have advised on a host of similar measures at both the state and federal level that…