Well said Pericles:

To the author I wanted to focus on this point:

"Another claim argues that human rights are imbued with morality and therefore as a community we could not possibly all agree to a set of rights."

This is a very strong point that I think deserves much more of an explanation, because a good many rights detract directly from another form of right- all we do is attempt, if we can, to mutually agree which is more important to ourselves personally (that is, as far as every person with a say in the matter is concerned).
I'll list a few examples and ask any who read this which they prefer (no, these aren't trick questions, these are issues that are seriously perceived to be valued by different people- and often, put it significantly different legal contexts in different first-world countries).
-Rights of property renters vs rights of tenants to own properties?
-Freedom of movement vs local land title, sovereignty or bush regeneration
-Freedom of information vs, occasionally, privacy issues (especially difficult in criminal cases)
-Free enterprise vs compulsory public regulation and consultation
-Right to own private property vs right to publicly own assets
Just a few to remain brief- but some specific problems which require a very precise balance to (in order to be just) reflect as closely the broad moral leanings of the citizens.