The legality of the program was addressed by Presidential candidate Rep. Ron Paul (R-TX) who denounced the Obama administration for the controversial tactic.
"According to the Fifth Amendment of the U.S. Constitution, Americans are never to be deprived of life, liberty, or property without due process of law. The Constitution is not some aspirational statement of values, allowing exceptions when convenient, but rather, it is the law of the land. It is the basis of our Republic and our principal bulwark against tyranny. Last week's assassination of two American citizens, Anwar al-Awlaki and Samir Khan, is an outrage and a criminal act carried out by the President and his administration." Rep. Paul said in an Oct. 10, 2011, statement.
Officials have previously acknowledged that the Justice Department and the National Security Council were highly involved in drafting the authorities when they were first disclosed by DNI Blair.
Before his death, top counter-terrorism officials acknowledged that Awlaki and al Qaeda's affiliate in Yemen to be the top terrorism concern to the United States.
"I actually consider al Qaeda in the Arabian Peninsula with al-Awlaki as a leader within that organization probably the most significant risk to the U.S. homeland," Michael Leiter said before Congress last February when he was the Director of the National Counterterrorism Center.
Awlaki was linked to numerous terrorism investigations in the United States serving as a key individual espousing terrorist acts in his sermons which were posted online. Fort Hood shooter Nidal Hasan had exchanged emails with Awlaki before he killed 13 people and wounding more than 30 in an assault on Fort Hood in November 2009.
Awlaki is believed to have inspired several other terror plots in the U.S. as well and was key in providing operational instructions Umar Farouk Abdulmutallab in the attempted Christmas Day underwear bombing of Northwest flight 253.
In addition to the more recent strikes, the American government has killed U.S. citizens abroad since the War on Terror began. In 2002, the CIA killed American-born Kamal Derwish, a member of the "Lackawanna 6" terror group during a CIA Predator drone strike. Derwish was driving in a car with other members of al Qaeda, the government said.
In 2008, a missile strike in Somalia killed American Ruben Shumpert, a Seattle man suspected of being an Islamist radical. Shumpert was wanted by federal authorities on gun and counterfeit currency charges. He had agreed to plead guilty but fled the country days before sentencing in 2004.