And, under current law, KSM et. al. are enemy combatants. The law is probably too loose with the term...

They can be tried by commissions -- Congress just passed a new commission law after all. [...] Under current law, they also can be detained indefinitely as fighting goes on in Afghanistan and elsewhere.
- jmatrixrenegade

Regarding combatants:

Regardless, no one is a combatant in the absence of armed conflict. According to the ICRedCross, "From an IHL [law of war] perspective, the term 'combatant' or 'enemy combatant' has no legal meaning outside of armed conflict."

[Links, and the definition of both types of armed conflict here: http://letters.mobile.salon.com/opinion/greenwald/radio/2009/08/04/hafetz/permalink/c8253a2a6b7df73f5c21d7330cd37203.html]

So you just made the case for 9/11 being the beginning of our Armed Conflict, rather than passage of the AUMF, because otherwise KSM is no "combatant."

If we were engaged, starting on 9/11 (not just as of the later Congressional AUMF), in a non-international armed conflict, in which our opponents violated the law of armed conflict by intentionally attacking civilians, they may be prosecuted for war crimes violations and/or for violations of the domestic law of the nation in which they acted (the U.S.). KSM, et al, as participants in a non-international armed conflict, had no immunity from [U.S.] domestic law for their 9/11 crimes, despite the fact that the act of being a fighter in such an armed conflict does not, on its own, make them war criminals, absent parallel violations of the law of armed conflict (such as attacking civilian targets).

But the only reason they "can" be tried by irregular commissions is because no one in a position to prevent such proceedings, has acted to prevent them - except, in part, because only part has reached it, the Supreme Court. It is entirely another matter as to whether the law provides for trial by 'drumhead justice'-akin military commissions convened (in past incarnations, at least) by military commanders in the field under their command responsibility to enforce the law of armed conflict/the UCMJ in the absence of courts, under conditions of effectively-lawless duress. [The Guantanamo Military Commissions are instead "convened" still to this day by "Convening Authority" Ms. Susan Crawford (good and loyal buddy of David Addington and Dick Cheney).]

[Aside: The ongoing habeas corpus hearings by federal judges are not reviews of the military commission proceedings, but are rather reviews of the government's power simply to detain alleged enemy fighters/criminals under the law of war. Thus far, the government has lost in 31 of 39 such hearings, under a low "more likely than not" standard of proof that the detention is lawful. This after 500 of 800 Guantanamo prisoners were already quietly released uncharged and untried during the Bush administration.]

To the degree the latest [commission] version does not match the UCMJ rules for courts-martial (I'd be interested how)... - jmatrixrenegade

Did you read Professor David Frakt's descriptions of how the commissions deviate from regular, UCMJ-mandated due process (which parallels civilian trial due process)?

http://emptywheel.firedoglake.com/2009/11/17/david-frakt-on-material-support-charges-and-military-commissions/

The 2009 Guantanamo Military Commissions explicitly include only non-citizens in their jurisdiction, and deny the rights our regular military courts-martial guarantee to enemy POWs (categorized detainees in an international armed conflict or yet-to-be-categorized detainees) to a speedy trial, against compulsory self-incrimination, and to a pre-trial investigation, in addition to all this:

http://seminal.firedoglake.com/diary/8097

This mess should have been sorted out years ago, with an integrated, torture-free demarcation process -- it should have been planned in advance, with legislation behind it that could withstand judicial scrutiny.
- commendatore

We had, and still have, such legislation and law: it's called the law of armed conflict (which we helped write after WWII), and Uniform Code of Military Justice-governed law-of-war courts-martial for accused enemy POWs (as well as American servicemembers).

The problem wasn't and isn't the lack of law, it was the politics (and the racism), and the failures of duty by our Congress and President. Congress and the President had to show how "tough" they were (John Wayne-style), so no international crime-fighting approach, though most effective and least costly, would suffice. No - instead they went to war against criminals, and intentionally warped, broke, and openly defied the law of armed conflict, as a direct result, thus far with virtual impunity from the international community, and certainly from our own Department of Justice.

I say again, we need a mechanism to determine the status and legal avenues of these people long before they wind up on American shores. - commendatore

Again, we had and have such a mechanism. It's called an "Article 5" GC tribunal, and provides for fair hearings by a "competent tribunal" to determine the "status" of "these [combatants]" before detention for the duration (at any status lesser than a POW, which would be the lesser Common Article 3 minimum humane treatment and due process standards), or are charged with an offense against the law of war (like perfidy or using civilians as shields).

Our military and CIA followed orders to disobey the law of armed conflict, and to skip such hearings, substituting rigged-for-the-jailer hearings like "Combatant Status Review Tribunals" instead - about which more here:

Lt. Col. Abraham also explained — as was backed up in October 2007 by a second whistleblower, an Army Major who had taken part in 49 [Combatant Status Review] tribunals — that unfavorable decisions were overruled by those in charge, who then convened a second tribunal to produce the desired result, and added that this is what had happened in the case of Mr. al-Ghizzawi. Lt. Col. Abraham and his fellow tribunal members were prohibited from taking part in any more tribunals, and a second, secret tribunal was held in Washington D.C., at which it was duly decided that Mr. al-Ghizzawi was an "enemy combatant" after all.
- Andy Worthington

http://www.andyworthington.co.uk/2009/11/22/justice-department-pointlessly-gags-guantanamo-lawyer/

What's left? - zeroworker

I took a stab at the problem - at sig.