Here's my understanding of natural rights:

Natural rights are those rights inherent to a being.

Those rights are inalienable if they may not be overridden by social contract.

Without some sort of deity, I don't understand how inalienable natural rights can be defined in any way that is useful (legally). Our natural right would seem to be "do what thou wilt", and this right would seem to always be inalienable--we can always do what we want regardless of what social contract we have entered into. This isn't useful though, because we want our social contract to be binding.

From the perspective of one who wishes the well-being of all, we might consider that "life, liberty, and the pursuit of happiness" are great rights that all people should have, but I don't understand how we can reasonably define these as inalienable natural rights apart from our general right to "do what thou wilt".

Have any contemporary philosophers addressed this issue?