H. J. McCloskey on Punishment of Cruelty to Animals

[T]here is another class of cases where the state is accorded the right to interfere with the individual when he is not interfering with any other person, namely, where cruelty to animals is involved. We accept that the state has the right to ban cruelty to animals, even when such cruelty is in the interests of the person being cruel, for example, of the greyhound owner who trains his dog on cats, first removing the cat's claws to protect his dog from injury, or of the householder who half-starves his dog so that he can have an extra beer or two, or of the person who hunts kangaroos, wounding many and killing a few, for the fun of the sport. Legislation forbidding cruelty to animals represents the use of coercion against the interests of the individual coerced, and not to further the interests of any other person (it may do so but need not to be justified). Yet it is legislation that few of us should wish to condemn as lacking in justification. (It is, of course, arguable that the liberal who is prepared to allow state legislation against cruelty to animals is compromising his liberalism, even though it is typically in liberal societies that we find such legislation. Certainly a strange mode of justification is offered along the lines of interpreting animals as weaker members of the community, as individuals who cannot protect their own interests, and who therefore need the sort of protection extended to others such as children, lunatics, etc., who cannot protect their interests. Animals, in fact, are not members of the community, they are not weaker individuals in the sense that children are, and this is recognised in very many ways.)

(H. J. McCloskey, "Some Arguments for a Liberal Society," Philosophy 43 [October 1968]: 324-44, at 330-1)