The Obama Administration authorized the killing of a United States citizen without a trial or judicial review.  The New York Times states:

“The notion that the government can, in effect, execute one of its own citizens far from a combat zone, with no judicial process and based on secret intelligence, makes some legal authorities deeply uneasy. … President Obama, who campaigned for the presidency against George W. Bush-era interrogation and detention practices, has implicitly invited moral and legal scrutiny of his own policies.”

For more, see http://www.nytimes.com/2010/05/14/world/14awlaki.html?hp