God Requires Us To Tackle Evil.

When - as we inevitably shall - capture members of ISIS, what is to be done with the ones who have coldly stripped innocent individuals of life in order to place clips onto the Internet? Placing them in prison does not remove their evil from the planet - indeed, it may well proliferate there. Executing them does. This is not possible through normal court systems - such publicity and martyr-making would be undesirable in the extreme.

It is profoundly tragic to have to move justice to behind closed doors in any free society - and in an intellectual sense would be a kind of victory for the forces of evil - but we may have no alternative. We do not want the military summarily 'bumping off' terrorists on the quiet without being answerable for their actions. Nor do we want the military being turned into bêtes noires and being bullied on the pages of The Guardian, The Mirror & The Independent, however many years down the line.
No. Properly constituted military tribunals conducted in camera and completely without any publicity, should be granted the necessary powers - but only under proper safeguards and in the extremely limited area of terrorists who have murdered to advance their cause. 
Such tribunals should be monitored closely as they too would need to be answerable - but to whom is most tricky. The Attorney General, perhaps? Better minds than mine should be dedicated to creating a system to work efficiently and with the maximum attention to the needs of basic justice. We would have to try hard to avoid the ravages possible where rough justice may be enacted. It would be naive to believe that such things would not occur. What I want is actually more attention to the needs of fairness.
The timescale would need to be weeks at the very longest - but preferably days. In extremis, the first decision would have to be the only decision. 
As one dedicated to open justice, what I have written grieves me greatly but I do not want the alternative - secret commandos killing terrorists on their own say-so. We do not want the GAL kind of system which operated in Spain against ETA twenty or so years ago emerging. That is a far greater threat within a democracy.
http://www.academia.edu/1768223/Dirty_War_in_Democracy_The_Stategic_Interaction_between_the_GAL_and_ETA