What we hear now, from Canadian apologists for treatment of Afghan prisoners - the transfer to Afghan custody in dubious and probably illegal circumstances - is that it wasn't "practical" to look after the prisoners ourselves.
How that is a defence? First, Canadian troops took prisoners in Europe in World War 2, and sent them across what is usually called the "U-boat infested" North Atlantic to POW camps in Canada, some on the Lake of the Woods which is in the centre of the continent, about as far away from Europe as possible. Second, I've read the Third Geneva Convention, and "practical" isn't a defence, any more than the fact that Hitler said the Hague Conventions didn't matter was a defence for Keitel. Third, if Canada got into a shooting war without considering its obligations under the Third Geneva Convention, then somebody should answer for that, and it's not the Canadian Military Police on the ground who seemed to have had a much clearer idea of the Convention than the chain of command in Ottawa do now, or for that matter, do their political superiors, meaning the Minister of National Defence and his Parliamentary Secretary.
Here are the rules for United Nations forces whether engaged in "peace-keeping" or "peace enforcement." People keep throwing around the term "UN-mandated mission" in a promiscuous way, as if that made everything OK, but in fact, this is not a UN mission, and the United Nations has not signed a status-of-forces agreement with Afghanistan, which leaves ISAF flying on its own legally, doesn't it? Yes, there is UN Security Council Resolution 1386 and all that, but if that is regarded as legal authority for taking prisoners, then the Security Council is on the hook for grave breaches of the Geneva Conventions, and ISAF is on the hook either way, isn't it?
And the Third Geneva Convention seems particularly clear where the duty of care resides for prisoners:
