Jeep 2004 Liberty - Manual (Page 22)

Child Protection Locks
The rear doors of your vehicle are equipped with child
protection locks. If you push up on the lever on the open
edge of the door it cannot be opened from the inside of
the vehicle. Push the lever down to disengage the child
protection locks.
WARNING!
Avoid trapping anyone in the vehicle in a collision.
Remember that the rear doors can only be opened
from the outside when the child protection locks are
engaged.
22 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE