My daughter bought new tail lights for her 2003 4-door Honda Civic. 
They are each 2 pieces; one part goes on the trunk and we have
successfully replaced that piece.  We are having a problem replacing
the other one - it is the brake light part that is attached to the car body
itself.  We cannot get the original tail light off.  We have undone
the three nuts holding the tail light under the trunk liner, removed
the bulbs & pieces the bulbs screw into, and also undone a screw that
is accessible from underneath the car.  We're afraid to really pull on
the tail light in case it breaks.  I tried to find proper instructions
on the internet but the best I could find was someone else looking for
the same answer (http://www.automotiveforums.com/t230297.html and
http://forums.vmag.com/pm-0499/messages/2870.html).  I am
looking for clear, step-by-step instructions on how to remove the
original tail light.