Loubani and Greyson found themselves inside the Fateh Mosque, which had become an ad hoc sanctuary, field hospital and morgue.
During the dozen years or so since the R2P concept was formulated, its application has been complicated and ad hoc.
Leaving decisions to the ad hoc judgment of such regulators only opens the door to future errors.
Latin, literally "for this (specific purpose)."
Contrived purely for the purpose in hand rather than planned carefully in advance. E.g. "We didn't know what to do about the sausage rolls, so we set up an ad-hoc committee".