The new rules have existed since 1912
Join the military and they will teach you the rules. Repeatedly.
It was a long time ago but the instruction on the treatment of POWs was pretty cut and dried when I was in basic: you are supposed to safeguard ANY prisoner in your care until properly discharged to authorities in the rear. Someone wants to harm the prisoner? You are duty-bound to defend their life with yours. Any means necessary.
It was a difficult class, and we must have done the drills all afternoon until a tired recruit started swinging to connect with the nose of the DI “harassing” our prisoner.
“That’s a start. And you’ll expected to do better than that!” Then it hit us. And we started using our fists and rifle butts to protect the “prisoners.” No, more, “Hey...” It was “Get the F— back!” Followed by a lusty swing. Sometimes it hit. Once everyone had their turn, lesson over, a short test, and back to the cattle-trucks.