Trunk light

There are 2 wires going to the double pole bulb socket one wire is constant hot to the bulb. The other wire is the ground that goes to the switch. If you ground the black wire the light goes on. All the switch does is grounds that wire. If the light doesn't go off with the switch depressed the switch is shorted to itself.

So if you unplug the switch the light should go out If you touch the wire to ground it should light up. Do you have a double pole bulb installed. That is what goes in that socket.

Could the bulb socket be shorted . Because the light should not go on without the black wire grounded.