The major financial frauds of our time have focused attention on the difficult task of defining what the US Supreme Court meant when it eliminated "aiding and abetting" liability for private litigants with its 1995 decision in Central Bank of Denver v First Interstate Bank. The distinction the court drew between actionable primary liability, and non-actionable secondary liability for those who merely aid and abet a financial fraud, has proven to be an elusive one for the lower courts. Yet it is of vital interest to financial institutions, professionals and even to ordinary purchasers of goods or services, all of which face enormous potential liability when an issuer is alleged to have engaged in a financial fraud. Banks have paid approximately $5 billion in settlements related to the collapse of WorldCom, for example, while three banks have paid a total of $6.6 billion in settlements relating to the demise of...