The G20 summit is under way in Cannes. While the European sovereign debt crisis is at the top of the agenda, one of the more noteworthy topics being discussed is a so-called "Robin Hood Tax," a financial transaction tax on stocks, bonds and derivatives trades. Microsoft founder and philanthropist Bill Gates is at the summit to address world leaders in support of the tax, which he says could be utilized to help developed nations meet their global aid obligations to the world's poorest countries. Earlier this week two Democrats, Congressman Peter DeFazio (D-OR) and Senator Tom Harkin proposed this very plan as a way to deal with the deficit.Rep. DeFazio talks about why he thinks the tax in necessary. New York Times Wall Street and finance reporter Louise Story looks at the tax from a global perspective.