Antebellum refers to the period leading up to the American Civil War, and Jus ad bellum for those of us not trained in Latin is justice to war. Or in other words, is a branch of philosophy concerned with creating a framework in which the decision to resort to war can be meaningfully debated and morally supported (or not supported). As an actionable brand of philosophy which provides moral license to kill, there is good reason to have at minimum, a basic understanding. Here is the wikipedia entry. Though what I mean by basic understanding is not a catechistic recitation of the published criteria or flowchart which can offer a yes or no answer, but rather recognizing that the "to war or not to war" decision is one which virtually all of us would answer yea or nay to, depending on the situation. And as such, the protester can not dumbly carry the anti-war banner and the supporter can not dumbly carry the flag of national security.
And to consider actual history in the making:
1. Is the War On Terror in Afghanistan justified? If not, was WWII justified (we did bring the fight to foreign shores)?
2. Are we justified in not intervening militarily in Darfur? If so, how is Iraq different?