David Cay Johnston: Closing Wall Street's Casino

A superb example of a sound rule in law and economics that needs reviving, because it can halt the rampant speculation in derivatives, is the ancient legal principle that gambling debts are not enforceable through court action.

Not so long ago — before casinos, currency and commodities speculation, and credit default swaps became big business — U.S. courts would not enforce gambling debts.

Restoring this principle offers a simple way to shrink the rampant speculation in derivatives that was central to the 2008 meltdown on Wall Street.