Banks are still banned from dealing in securities, which makes them weaker than they otherwise would be.

ECONOMIST: Japan's economy

Now the real punishment comes by Cuomo wanting a few more dollars from Rattner as well as banning him from dealing in securities in the state of New York.

FORBES: Bans and Censures for Rattner and Rangel Respectively

And courts have often looked askance at broadly using the laws on securities fraud to go after people outside of the business of issuing, underwriting and dealing in securities.

WSJ: Review & Outlook: Payback for a Downgrade?

In short, investors are dealing with a new set of complex securities, based on loans to a new type of borrower, where the loan terms and conditions may not be clear and at a time when house prices are falling nationally for the first time in living memory.

ECONOMIST: The costs of clearing up the subprime crisis

For several years, criminal authorities have wrestled with challenges caused by communication about illicit activities, from securities fraud to drug dealing to terrorism, through messaging tools in social networks, videogame systems and other digital platforms.

WSJ: Wall Street Battles States on Social-Media Protections

After the Wall Street crash of 1929, it took four years before Congress passed the Glass-Steagall act, which split commercial banking from securities dealing. (Before the legislation bank deposits were frequently diverted in support of new issues by commercial bankers' investment-banking colleagues.) Other restrictive rules continued to be made until 1940.

ECONOMIST: Investment banks

At present, a commission set up by Italy's treasury is writing a new law covering securities dealing, markets and corporate governance, which is supposed to come into force in February.

ECONOMIST: Italy��s stock exchange

On July 28th a new securities law will come into effect in Mexico, tightening provisions against corporate self-dealing and toughening the penalties.

ECONOMIST: Shares in emerging economies