The following is an excerpt from an article regarding Insider Trading, see the second paragraph regarding US Congress:
"American insider trading law
The United States has been the leading country in prohibiting insider trading made on the basis of material non-public information. Thomas Newkirk and Melissa Robertson of the U.S. Securities and Exchange Commission (SEC) summarize the development of U.S. insider trading laws. Insider trading has a base offense level of 8, which puts it in Zone A under the U.S. Sentencing Guidelines. This means that first-time offenders are eligible to receive probation rather than incarceration.
Members of the U.S. Congress are not exempt from the laws that ban insider trading, however, they generally do not have a confidential or fiduciary relationship with the source of the information they receive and accordingly, do not meet the definition of an "insider".
Common law
U.S. insider trading prohibitions are based on English and American common law prohibitions against fraud. In 1909, well before the Securities Exchange Act was passed, the United States Supreme Court ruled that a corporate director who bought that company’s stock when he knew it was about to jump up in price committed fraud by buying while not disclosing his inside information.
Section 15 of the Securities Act of 1933 contained prohibitions of fraud in the sale of securities which were greatly strengthened by the Securities Exchange Act of 1934.
Section 16(b) of the Securities Exchange Act of 1934 prohibits short-swing profits (from any purchases and sales within any six month period) made by corporate directors, officers, or stockholders owning more than 10% of a firm’s shares. Under Section 10(b) of the 1934 Act, SEC Rule 10b-5, prohibits fraud related to securities trading.
The Insider Trading Sanctions Act of 1984 and the Insider Trading and Securities Fraud Enforcement Act of 1988 provide for penalties for illegal insider trading to be as high as three times the profit gained or the loss avoided from the illegal trading.
[edit] SEC regulations
SEC regulation FD ("Fair Disclosure") requires that if a company intentionally discloses material non-public information to one person, it must simultaneously disclose that information to the public at large. In the case of an unintentional disclosure of material non-public information to one person, the company must make a public disclosure "promptly."
Insider trading, or similar practices, are also regulated by the SEC under its rules on takeovers and tender offers under the Williams Act."
The following link refers to the current support for a proposal to ban this exception:
http://www.ft.com/cms...c0.html#axzz1f2sfyAoG