Yesterday we heard word that Jarvan might be a little too strong. Statikk comes to the forums to let us know its not really a nerf they will be giving him, but more of a big fix.
We're not nerfing Jarvan, at least not directly.
In the upcoming patch, we are fixing a bug that was released last patch where his passive is dealing max Health damage against minions and monsters instead of current Health. This is artificially inflating the speed of his clear times and increasing his effectiveness on bigger objectives like Dragon and Baron as well which is an advantage Jarvan simply doesn't need considering all the other things he brings to the table.
Let's be clear though, Season 3 has changed the landscape of the game. Though someone like Jarvan has stayed untouched for a long time and has not been an issue up until this bug, it could be fully possible that a champion needs to be addressed due to other changes that have occurred in the game. Just like some champions have gotten weaker (for example as you guys say Irelia), some have gotten stronger. We need to constantly assess things within the context of the current state of the game (not to say that we don't take into account potential future states of the game in our decisions).
Once again, we're not directly nerfing Jarvan, but we will be monitoring him closely following the upcoming bug fix.