Rights, Animals, and Vampires

This comes from a conversation about True Blood and the Vampire Rights Amendment. Should vampires have rights, when they're not human? Do rights begin with laws, or do they exist before they are legislated - and if so, where?

It seems obvious enough to me that non-human animals should have rights. Not only human-like animals like vampires, obviously, but also all other complex animals (there is the question of line-drawing, with insects and things like that, but let's leave that aside for now). I also asserted that animals do have rights: the right not to be tortured or cruelly harmed. In other words, it's illegal for people to cause needless suffering to animals. Doesn't that constitute a right, for animals, to freedom from nedless suffering? Or do rights have to be framed as rights?

The US Bill of Rights is a complex example. Take the first clause of the first amendment: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof." It's totally not phrased as a right for the people to the free exercise of religion. But it seems to be meant for that effect, and that's how it's generally interpreted; indeed, its presence in the Bill of Rights implies that we're dealing with a right here, despite the phrasing.

The idea of Bills of Rights, and rights law in general, seems to be to defend rights that already exist. But I'm not sure about that either.

The distinction between rights, which are attached the potential victim (i.e. your rights can be infringed), and prohibitions, attached to the potential act of infringement, seems to me a false distinction. We're really dealing with a structure of behaviour, where surely it's the outcome that matters most. So, if the outcome of a law is that I can freely practice my religion, then I have that right. I think you could characterise this position as pragmatist: it's a question of outcomes and structures, not of 'essential' or 'fundamental' truths.

It seems to me the question really worth asking here is not "what rights do we have," but "what laws should we have"?