What does it mean to say that someone has 'inalienable rights' or 'inviolable rights'? One often finds people talking about these things as if (e.g.) having a right to liberty meant no one could ever do anything to infringe on one's liberty. But this is not what the phrases have traditionally meant. To say that someone has 'inviolable rights' simply means that they have rights too sacred or too important to be broken by force or violence; and to say that someone has 'inalienable rights' (or 'unalienable rights') is to say that they have rights that cannot be handed over to someone else. The reason Jefferson appealed to 'inalienable rights' in the Declaration of Independence can be seen in context:
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.--That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, --That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness.
The appeal to rights that cannot be alienated is there to insist that there are some rights citizens cannot simply turn over to the government - to 'alienate' means to sell off or give over to someone else. When we form political societies, we hand over or alienate rights to our government, so that it can do the work we all need it to do. Some rights, however, cannot be alienated at all: we cannot lose them by giving them to someone else. No government can claim to have taken away or received its people's rights to life, liberty, or the pursuit of happiness; the people cannot give such rights away to the government under any circumstances. Inalienable rights, in other words, are rights no one can waive. The Declaration needs to appeal to rights of this sort to allow a right of the people to abolish or alter their government, because if it appealed to rights that citizens gave away to their government, it obviously couldn't support the conclusion of the above line of thought.
Likewise, inviolable rights are rights that are too important or sacred to be infringed by violence. It does not follow from our having an inviolable right to liberty, however, that no one will ever have the right to curtail our liberty; it only means they cannot do violence to our right to liberty. Now, it may well be that we have inviolable rights to x that are such that no one can ever have the right to take away or curtail x. It's possible to argue, for instance, that our inviolable right to life is such that no one can ever have the right to put us to death; but this requires further argument. The right's being inviolable is not sufficient argument; for it may well be that there are ways to curtail your liberty that don't do violence to your right to liberty (e.g., if there is some right that is more fundamental than the right to liberty, and upon which the right to liberty was founded, curtailing someone's liberty to protect that right wouldn't be doing violence to the right to liberty, because the right to liberty itself requires the protection of that more fundamental right).
