The current carnage on Wall Street, with dire spillover effects on Main Street, is the result of a failed ideology -- the idea that financial markets could regulate themselves. Serial deregulation fed on itself. Deliberate repeal of regulations became entangled with failure to carry out laws still on the books. Corruption mingled with simple incompetence. And though the ideology was largely Republican, it was abetted by Wall Street Democrats.

Why regulate? As we have seen ever since the sub-prime market blew up in the summer of 2007, government cannot stand by when a financial crash threatens to turn into a general depression -- even a government like the Bush administration that fervently believes in free markets. But if government must act to contain wider damage when large banks fail, then it is obliged to act to prevent damage from occurring in the first place. Otherwise, the result is what economists term "moral hazard"-- an invitation to take excessive risks.

Government, under Franklin Roosevelt, got serious about regulating financial markets after the first cycle of financial bubble and economic ruin in the 1920s. Then, as now, the abuses were complex in their detail but very simple in their essence. They included the sale of complex securities packaged in deceptive and misleading ways; far too much borrowing to finance speculative investments; and gross conflicts of interest on the part of insiders who stood to profit from flim-flams. When the speculative bubble burst in 1929, sellers overwhelmed buyers, many investors were wiped out, and the system of credit contracted, choking the rest of the economy.

In the 1930s, the Roosevelt administration acted to prevent a repetition of the ruinous 1920s. Commercial banks were separated from investment banks, so that bankers could not prosper by underwriting bogus securities and foisting them on retail customers. Leverage was limited in order to rein in speculation with borrowed money. Investment banks, stock exchanges, and companies that publicly traded stocks were required to disclose more information to investors. Pyramid schemes and conflicts of interest were limited. The system worked very nicely until the 1970s -- when financial innovators devised end-runs around the regulated system, and regulators stopped keeping up with them.

Seven Deadly Sins of Deregulation -- and Three Necessary Reforms
The most interesting part of this article is in Sin Three:

"The Democratic Congress anticipated this problem in 1994, when it passed the Homeownership Opportunity and Equity Protection Act. This prescient law required the Federal Reserve to regulate the loan-origination standards of mortgage companies that were not otherwise government-regulated. But Alan Greenspan, a free-market zealot, never implemented the law. And when Republicans took over Congress in 1995, they never called him on the carpet.

There you have it. The Democrats tried to fix the problem but the Republicons stopped them.