Islam forbids the consumption of all parts and by-products of any porcine species, blood from any animal, the meat of any animal not slaughtered according to halal practices, carnivorous animals, birds of prey, human tissues and alcohol. Any animal that is killed prior to slaughter is not considered halal.
Halal is an Arabic term which simply denotes something as lawful or allowable by Muslim religious law. Of primary concern is the method of dispatching an animal prior to slaughter. Common practice involves invoking the name of God prior to slaughter and cleanly severing the carotid artery while hanging the animal from its hind legs and allowing it to drain of blood quickly. This practice raises some concerns among animal welfare organizations due to the potential for the animal to suffer prior to complete exsanguination.
Though the specific requirements laid out by the Qu'ran do not expressly forbid the practice of stunning, the argument exists that this approach damages the animal or puts it at risk of death too long before slaughter begins. Unfortunately, as of 2014, no centralized oversight organization exists to certify a meat supplier as meeting halal requirements, leading to a wide variety of practices that do not always reflect one another.