How do i fix my brake lights that never turn off?

I have a 2003 Ford Escort ZX2. The other day when i got home and turned off the car, i noticed that the brake lights were still on. I checked the fuses but maybe i'm missing something else. Everytime i stop the car i have to unplug the battery so that i won't get stranded. How do i go about fixing the brakes lights from not turning off?