Writing in USA Today, Glenn Reynolds, the Instapundit, makes some great points regarding leaking and legitimacy:
As recently reported by the McClatchy Newspapers, the Obama administration views whistleblowing and leaks as a species of terrorism. According to McClatchy: "President Obama's unprecedented initiative, known as the Insider Threat Program, is sweeping in its reach. It has received scant public attention even though it extends beyond the U.S. national security bureaucracies to most federal departments and agencies nationwide, including the Peace Corps, the Social Security Administration and the Education and Agriculture departments. It emphasizes leaks of classified material, but catchall definitions of 'insider threat' give agencies latitude to pursue and penalize a range of other conduct. … Leaks to the media are equated with espionage."…
The freer people are to blow the whistle on wrongdoing, the more we can assume that when no whistle is blown, things aren't so bad. The more the government cracks down on whistleblowers, the more likely it is that they've got something to hide.
This system isn't perfect. Leakers can abuse their power for reasons of revenge, ego, or politics—but then, so can congressional overseers, or attorneys general, or presidents. And the strong Democratic tilt to the career civil service means that Democratic presidents probably get less leaking than Republicans (and, when leaks happen, less coverage from the Democratic-leaning press).