Jacks are a difficult poker hand to play in position because, facing a re-re-raise, it's difficult to know whether you're up against a pair of queens or kings or even ace.  The best way to determine whether you are is to get a feel for how loose your opponents are playing, his general betting patterns and tells, and his relation to the entire table. Also, you should pay attention to past history of the table, which would tell you if he/she is steaming after a bad beat or whatever he may be doing at the time.

As an example, say you raise to three big blinds and your opponent in late position comes over the top for nine big blinds.  What is his past history of betting?  Does he/she make these kind of bets without a made hand? Does he/she have a poker strategy? Is he/she from a rich foreign country in where people have a general disdain for American money? 

Say he/she just lost a massive pot all-in with A-10 vs. A-9.  He may be steaming, and may be raising a weaker range of hands, say A-10 to A-K and all pairs above 10s, as well as face cards like K-Q, Q-J, and K-10.  Here’s where you have to start paying attention to some betting tells like the size of his bet in relation to the pot, and how quickly he/she made it.  I would suggest just calling with your jacks and see if an overcard flops, and then tread carefully.  It get's really tricky when all undercards flop, and it turns into a game of who has the bigger pair?  Here is where you have to observe tells like how quickly he is betting or how big his bet.  He may be steaming; he may be bluffing, but also pay attention to how he views your actions.  It turns into a mind game in which each player is trying to feel the other one out.  Good luck at the poker tables!