NBC News published this Department of Justice confidential white paper on February 5, 2013, which outlines the legal framework that would allow the U.S. government to "use lethal force in a foreign country" against a U.S. citizen highly involved with al-Qaeda or its associates. A bipartisan group of U.S. senators requested all classified documents related to the legality of targeted killings of Americans be released.
Excerpt from the PDF published by NBC News:
"In conclusion, it would be lawful for the United States to conduct a lethal operation outside the United States against a U.S. citizen who is a senior, operational leader of al-Qa'ida or an associated force of al-Qai'da without violating the Constitution or the federal statues discussed in this white paper under the following conditions: (1) an informed, high-level official of the U.S. government has determined that the targeted individual poses an imminent threat of violent attack against the United States; (2) capture is infeasible, and the United States continues to monitor whether capture becomes feasible; and (3) the operation is conducted in a manner consistent with the four fundamental principles of the laws of war governing the use of force. As stated earlier, this paper does not attempt to determine the minimum requirements necessary to render such an operation lawful, nor does it assess what might be requierd to render a lethal operation lawful, nor does it assess what might be required to render a lethal operation against a U.S. citizen lawful in other circumstances. It concludes only that the stated conditions would be sufficient to make lawful operation in a foreign country against a U.S. citizen with the characteristics described above."