The debate over when meat is halal and whether it should be clearly labelled has been put back on the agenda by vets and animal welfare campaigners who want all animals slaughtered for food to be stunned before killing.
The Arabic word halal means permissible, and the rules of slaughter are based on Islamic law. The animal has to be alive and healthy, a Muslim has to perform the slaughter in the appropriate ritual manner, and the animal's throat must be cut by a sharp knife severing the carotid artery, jugular vein and windpipe in a single swipe.