It all depends on the officer. Will you get pulled over just because of bumper height? Probably not. Are they going to write you a ticket for it if you are already pulled over for something else? Maybe, if they decide to throw the books at you.
I wouldn't be afraid to put a 4 inch lift on your Jeep.
1994 YJ 2.5L AX5 231 - SOA AAL HP30 F8.8 4.88's 35's - SOLD
2000 XJ 4.0L AW4 242 - 4.5 RC Flipped Leafs for Stretch Comp Cut 35's - SOLD
1988 MJ 4.0HO AW4 231 - HP30 C8.25 - BDS 6.5 LA 35 KM2 - 99 XJ clip and interior - SOLD
1997 TJ 4.0L AX15 231 HP30 F8.8 - NEW PROJECT