I believe it is this principle that must inform our law-making and application of those laws. For this is the only formulation of the doctrine of human rights that takes seriously both the notion of 'human' and 'rights'.
Whenever we look closely at some legal justification for an act which we know intuitively to be abhorrent, we can usually find that it involves an abrogation of human rights: an implicit assumption that, for the purpose of some law or other, people will not be counted amongst the fully 'human', or that rights they might hold at other times will be suspended at another particular time. (Read more over the fold)
This abrogation of human rights becomes a habit. Some people are denied legal equality based on their choice of life partner, because some long-ago lawmakers neglected to treat theirs as an equal human relationship before the law. Others are denied the dignity of being treated as legal adults, having their income and expenditure forcibly managed by government -- the "crime" of being chronically poor is deemed by some lawmakers to be sufficient justification for removing a basic human right of dignity and respect.
But this denial of human rights also extends beyond the individual. What do we make of governments supporting corporations against the will of communities who don't want mining or CSG wells on their productive agricultural land? What do we make of governments forcing democratic bodies such as councils to be forcibly amalgamated against the democratic wishes of the people in these domains?
It is clear that the denial of human rights by lawmakers and politicians is a very slippery slope that leads to monstrous outcomes.
And it may just be that when we successfully develop the habit of mind and the moral courage consistently to recognise and respect the rights of all human beings, all the time -- that we will be ready to take the next step of recognising and respecting the inherent worth of the animals, plants, biomes and ecosystems in their own right (and not only because they happen to sustain the existence of all human beings on planet Earth...)