Jus ad bellum - Jus in bello

Jus ad bellum

Literally: "law before war". The applicable law before armed conflict occurs. It refers to a set of rules that determine under which circumstances states may legally use force against each other. The main source can be found in the Charter of the United Nations.

Jus in bello

Literally: "law in war". The applicable law during armed conflict, also referred to as ‘international humanitarian law’, the ‘law of war,’ or the ‘law of armed conflict.