AG Holder then addresses the problem of US citizens who are members of AQ (or an associated group). Chesney (his post at Lawfare linked in part 1) presents his analysis with his comments in regular face and Holder's statements in italics (both are bolded as in Chesney's post).

First, as to the general rule:

[Chesney] At a minimum, force can be used against a citizen in the following circumstances…. Against that backdrop, Holder then describes a set of circumstances in which deadly force lawfully can be used against a citizen. Note that his language pointedly does not exclude the possibility of using force in other circumstances:

[Holder] Let me be clear: an operation using lethal force in a foreign country, targeted against a U.S. citizen who is a senior operational leader of al Qaeda or associated forces, and who is actively engaged in planning to kill Americans, would be lawful at least in the following circumstances:

First, the U.S. government has determined, after a thorough and careful review, that the individual poses an imminent threat of violent attack against the United States;

second, capture is not feasible; and

third, the operation would be conducted in a manner consistent with applicable law of war principles.

[Chesney] Restating the test… I wish the preceding paragraph had been formulated more clearly, but in any event it seems to me that there are as many as seven elements in that statement. Read literally, Holder has defended targeted strikes against a citizen where the following conditions are met: the person must be (i) located abroad rather than in the United States, (ii) have a senior operational role (iii) with al Qaeda or an al Qaeda-associated force, (iv) with plotting focused on the death of Americans in particular, (v) with the threat being “imminent” (though not that this is defined in a broad sense, consistent with Brennan’s fall 2011 speech), (vi) with no feasible option for capture, and (vii) all subject to law of war principles. And, again, note that he carefully did not describe this as the outer boundary of lethal force authority when it comes to a citizen.
This sounds somewhat similar to the type of logic followed in Tennessee v Garner re: shooting a fleeing violent felon; except that it is based on Fifth Amendment Due Process (the viewpoint of some Garner dissenters; the majority went off on Fourth Amendment Search & Seizure) and does not require judicial approval at any stage. Again, to Chesney:

[Chesney] Rejecting a requirement for advance judicial permission… This part is interesting. The main line of criticism arising under the 5th Amendment has been that force cannot be used against citizens, on a pre-targeted, individualized basis, without the factual predicates for the action being put to the test in an independent, judicial forum. Holder rejects that conclusion, in part apparently in reliance on the decision by Judge Bates not to adjudicate the habeas petition brought by al-Awlaki’s father, in part on comparative institutional competence grounds to the effect that the executive branch has superior access to relevant information and expertise (and capacity to make quick decisions) with respect to targeting decisions, and comparative institutional legitimacy grounds to the effect that such decisions are a “core function” of the executive branch:

[Holder] Some have argued that the President is required to get permission from a federal court before taking action against a United States citizen who is a senior operational leader of al Qaeda or associated forces. This is simply not accurate. “Due process” and “judicial process” are not one and the same, particularly when it comes to national security. The Constitution guarantees due process, not judicial process.

[Chesney] The conduct and management of national security operations are core functions of the Executive Branch, as courts have recognized throughout our history. Military and civilian officials must often make real-time decisions that balance the need to act, the existence of alternative options, the possibility of collateral damage, and other judgments – all of which depend on expertise and immediate access to information that only the Executive Branch may possess in real time. The Constitution’s guarantee of due process is ironclad, and it is essential – but, as a recent court decision makes clear, it does not require judicial approval before the President may use force abroad against a senior operational leader of a foreign terrorist organization with which the United States is at war – even if that individual happens to be a U.S. citizen.
It is a given then that the Federal courts will not be involved in deciding these three areas covered by AG Holder - though not in great detail:

What is meant by “imminent threat”

[Holder] The evaluation of whether an individual presents an “imminent threat” incorporates considerations of the relevant window of opportunity to act, the possible harm that missing the window would cause to civilians, and the likelihood of heading off future disastrous attacks against the United States. As we learned on 9/11, al Qaeda has demonstrated the ability to strike with little or no notice – and to cause devastating casualties. Its leaders are continually planning attacks against the United States, and they do not behave like a traditional military – wearing uniforms, carrying arms openly, or massing forces in preparation for an attack. Given these facts, the Constitution does not require the President to delay action until some theoretical end-stage of planning – when the precise time, place, and manner of an attack become clear. Such a requirement would create an unacceptably high risk that our efforts would fail, and that Americans would be killed.

What is meant by “capture is not feasible"

[Holder] Whether the capture of a U.S. citizen terrorist is feasible is a fact-specific, and potentially time-sensitive, question. It may depend on, among other things, whether capture can be accomplished in the window of time available to prevent an attack and without undue risk to civilians or to U.S. personnel. Given the nature of how terrorists act and where they tend to hide, it may not always be feasible to capture a United States citizen terrorist who presents an imminent threat of violent attack. In that case, our government has the clear authority to defend the United States with lethal force.

What is meant by “consistent with applicable law of war principles"

[Holder] Of course, any such use of lethal force by the United States will comply with the four fundamental law of war principles governing the use of force. The principle of necessity requires that the target have definite military value. The principle of distinction requires that only lawful targets – such as combatants, civilians directly participating in hostilities, and military objectives – may be targeted intentionally. Under the principle of proportionality, the anticipated collateral damage must not be excessive in relation to the anticipated military advantage. Finally, the principle of humanity requires us to use weapons that will not inflict unnecessary suffering.
The first two limitations do not arise directly from the Laws of War. Again, they seem to indicate the discomfort of AG Holder and the WH with full bore application of the Laws of War to this unconventional warfare situation. As a counter-example, in the conventional WWII ETO situation, US citizens fighting with the German Army were treated the same as any other German soldier.

Regards

Mike