Step 1Combine the beer, lime juice, garlic, chipotles, salt, cumin and oregano and mix well. Stir in the oil. Reserve one-half cup for brushing on the chicken.
Step 2Place the chicken in a glass or other nonreactive baking dish and pour the marinade over it. Cover and marinate in the refrigerator for at least 1 hour and not more than 4. Return the chicken to room temperature 30 minutes before cooking.
Step 3Heat the grill. Lay the chicken on the grill, skin side down. Cook, basting occasionally with the reserved marinade, until the juices run clear, about 15 minutes on each side.