Both proc. You judge seal of wisdom on a mob, then cast a new seal when you need to regain mana bad. You need to do a melee hit on the mob with judgement every 30 seconds, to refresh the duration. This is what makes it hardt to keep judgements up on 2-3 mobs or more, when boxing. Personally I would never do it on more than 1 mob cause it takes to much attention away from healing and dpsing.

And there's one other thing I forgot to mention that makes paladin a kickass tank. Ranged taunt ability. It's a lifesaver for those patrols who happen upon your castergroup, when you dont have time/are unable to run back to grab aggro.

I just target the mob and use this macro:
/cast [target=targettarget, help] righteous defense