The view that animals have rights, for instance to decent treatment, is more controversial than the view that we ought to behave decently towards them. This is because to some thinkers the notion of a right involves the ability to make a claim against someone, or the consciousness of choice, or the possession of rationality, or the ability to enter into reciprocal relationships. If these connections hold, then not only animals but infants and the mentally retarded will be denied rights, and their needs and our obligations towards them must be discussed in other terms. The expanding animal rights movement has sought to assimilate our moral discrimination against animals to discrimination on grounds of gender or race: see speciesism.

http://ethics.sandiego.edu/Applied/Animals/index.asp A list of internet resources on animal rights

http://www.bbc.co.uk/religion/ethics/animals/ A survey of related religious, medical, and legal debates