Why a vote on taxing California’s billionaires is being watched around the world

In November, California will vote on a proposal to levy a one-off 5% tax on the wealth of all billionaires in the state.

Google co-founder and billionaire Sergey Brin has already spent US$100 million on political donations to a group opposing the tax. Brin is hoping to avoid a potential tax bill of US$13 billion, a return of roughly 130 to 1 if that investment is successful.