The Day America Died by Paul Craig Roberts:
"Many expected President Obama to re-establish the accountability of government to law. Instead, he went further than Bush/Cheney and asserted the unconstitutional power not only to hold American citizens indefinitely in prison without bringing charges, but also to take their lives without convicting them in a court of law. Obama asserts that the US Constitution notwithstanding, he has the authority to assassinate US citizens, who he deems to be a "threat," without due process of law.
In other words, any American citizen who is moved into the threat category has no rights and can be executed without trial or evidence."
http://lewrockwell.com/roberts/roberts328.html