I AM A MECHANICAL PROFESSIONAL ENGINEER LICENSED IN THE STATE OF CALIFORNIA. I WAS WITH AN INDIVIDUAL AT THE TIME THIS OCCURRED AS THEY ATTEMPTED TO OPEN THE BACK HATCH. UPON TRYING TO LIFT THE TAIL GATE THE INDIVIDUAL HEARD THE CLICK AND THE SLIGHT RELEASE OF THE LOCK FOR THE TAIL GATE. THEY WERE UNAWARE OF THE DEGRADED CONDITION OF THE SWITCHES COVER. UPON TRYING TO LIFT THE HATCH THEY FELT THEIR FINGERS "APPEAR" TO SINK INTO THE SWITCH. AFRAID OF SHOCK OR SUFFERING PHYSICAL ARM THE INDIVIDUAL ATTEMPTED TO PULL HAND AWAY FROM HATCH LATCH. DUE TO THE ADHESIVE NATURE OF THE DEGRADED SWITCH COVER THE FINGERS COULD NOT BE REMOVED IN THE NATURAL EXPECTED MOTION. THE ALTER MOTION RESULTED IN THE BREAKING OF THE LATCH SWITCH COVER AND THE INDIVIDUALS HAND BEING LAUNCHED IN A DIRECTION THAT FORTUNATELY ONLY RESULTED IN A SHOULDER SPRAIN. THIS LEFT THE VEHICLE BACK HATCH WITH A BROKEN COVER AND PREVENT THE USER FROM USING THE BACK HATCH UNTIL THE COVER AND SWITCH WERE /REPAIRED OR REPLACED. IT APPEARS THE RUBBER/GASKET/COVER FOR THE BACK HATCH LATCH SWITCH DEGRADES OVERTIME DUE TO UNKNOWN REASONS. IN THE HEAT IN THIS PARTICULAR CASE THE COVER BEGAN TO MELT AND DRIP OFF THE COVER/SWITCH. THE MATERIAL BECAME TACKY/STICKY ENOUGH TO BECOME ADHESIVE ENOUGH THAT SIGNIFICATION [IMPLYING THAT FORCE WOULD BE ENOUGH TO CAUSE SELF INJURY FOR SOMEONE THAT WAS NOT EXPECTING THE SITUATION TO DEVELOP AS SUCH.] FORCE WAS REQUIRED TO SEPARATE FINGERS FROM THE SWITCH (SEVERAL FT/LBS