During the 32 years I covered Washington for the Los Angeles Times, I learned that leaks from anonymous sources are crucial to informing the public. In the debate over what Karl Rove said when and to whom, and over the role of confidential sources in general, that must be underlined: Without leaks, without anonymity for some sources, a free press loses its ability to act as a check and a balance against the power of government. The stories that have depended on confidential sources, and often on classified information, are legend: Watergate in the Nixon administration, the Iran/Contra scandal and...