A Robin Hood Tax or Tobin Tax – named after Nobel Laureate economist James Tobin who proposed the idea in 1971 – is a is a tiny tax (0.03% to 0.05%) that would be levied on all financial market transactions. It would be applied to financial transactions traded through stock exchanges, futures exchanges or any facility established for the purpose of trading ("exchange trading").

Influential champions, including leaders of France and Germany, billionaire philanthropists Bill Gates and George Soros, former Vice President Al Gore, the consumer activist Ralph Nader, Pope Benedict XVI and the archbishop of Canterbury all support the idea. More than 1000 economists signed onto a letter in April 2011, urging G20 member nations to adopt a Tobin Tax.

Supporters tout the idea as a way to fund the unfulfilled Millennium Development Goals and, as of yet, empty Green Climate Fund, while also hampering needless financial speculation that destabilizes economies.

On March 23rd, 1999, the Canadian Parliament demonstrated world leadership when it passed motion M-239 urging Canada to "enact a tax on financial transactions in concert with the international community."

The Canadian motion sparked a global movement in support of controls on speculative capital. The Brazilian Parliament held hearings on the Tobin tax in August, 1999. The European Parliament debated the Tobin tax in January, 2000.

The Canadian government has acted only minimally on both letter and spirit of the motion passed in 1999. Stephen Harper, and the current Canadian government is one of the leading opponents of a Tobin Tax, despite support from other politicians like French President, Nicolas Sarkozy.