Flashback: Russ Feingold 'Pleased' Anwar Al-Awlaki Was Taken Out By Drone Strike

[ProSense]

22. From Senator Wyden's statement

“As I and ten other senators told the President yesterday, if individual Americans choose to take up arms against the United States, there will clearly be some circumstances in which the President has the authority to use lethal force against those Americans, just as President Lincoln had the authority to use force against the Confederate Army during the Civil War. At the same time, it is vitally important for Congress and the American public to have a full understanding of how the executive branch interprets this authority, so that Congress and the public can decide whether the President’s power to deliberately kill American citizens is subject to appropriate limitations and safeguards. Every American has the right to know when their government believes that it is allowed to kill them.

http://www.democraticunderground.com/10022320280
Beyond that precedent, it appears that the questions are designed to clarify the process and, primarily, to ensure that it's actually targeting people who take up arms against the U.S.