Although you could use this marinade on a whole chicken with both white and dark meat, it is pungent enough to stand up to dark meat alone.
Combine the orange juice, curry paste, mustard, salt, allspice, and pepper in a glass or ceramic bowl, stirring well to dissolve the paste and mustard completely.
Put the legs in a shallow glass or ceramic dish and rub the paste into the meat, being sure to coat well and to rub some paste under the chicken skin. Cover and refrigerate for at least 2 hours or overnight.
Prepare a charcoal or gas grill. Lightly spray the grill rack with vegetable oil cooking spray. The coals should be moderately hot.
Grill the chicken legs for 40 to 45 minutes, turning often with tongs. The chicken is done when the juices run clear when pierced with a fork or sharp knife, or when an instant-read thermometer registers 180°F when inserted in the thickest part of the legs. Don't let the thermometer touch the bone. Serve immediately.