Double Smiting

[Chronicled]

I think of it this way: would allowing this cause an unintentional loophole in the rules or create some other anti-balancing factor in the game? In this circumstance I'd say no, because smite damage is always based on class level so a multiclassed smiter won't be dishing out more damage than a single classed smiter. I wouldn't however, allow the Cha to attack roll to stack (I'm assuming the Justiciar has a similar bonus), as that would make the multiclassed smiter definitively better than the single classed smiter.

Meh, I'd allow them (and any other attack roll bonus) to stack. If they're multiclassing, they're unlikely to have more than 1 (maybe 2) smites per day, and they're putting all their eggs in one basket.

Also... Killoren Cleric with Destruction domain/Paladin/Justiciar/Crusader. Quintiple smite! (Some restrictions may apply. Void where prohibited by alignment.)