You can make more in a single stock trade than in a lifetime of public service. Congress has excluded investment income, such as stocks, from ethics limitations on income. The result is that members routinely make killings in the market in areas where they legislate. One study by the University of Memphis found that 75% of randomly selected members had "stock transactions that directly coincided with (their) legislative activity." Members have the unique ability to predict or even manipulate stock prices. Another recent study by Alan J. Ziobrowski of Georgia State University and three colleagues showed that U.S. senators beat...