Does a piece of paper have the power to protect and defend you, and deliver your enemies into your hands?
Nobody but a fucking idiot would claim that a piece of paper would or could defend them directly. The enforcement of law and the protection of rights is done by consensus and action of human conglomerates. The physical documents that record such things as declarations of independence, bills of rights, constitutions, resolutions, treaties, etc, have a far more mundane purpose, though just as important - they are an acceptably reliable record of decisions and promises that were made by such people. They are nothing more than an aide memoire; their purpose is to ensure the actions of governments remain consistent over time and that, when issues are debated and ruled upon, they can be checked for consistency with the original decisions that were recorded.
Large conglomerations of human beings have great power of action and decision, something a piece of paper does not and could never possess. However, a piece of paper has one great power that human conglomerates, notoriously, do not: precise recollection of the information entrusted to it (well, within reason - it'd still be sensible to keep a few backups and make newer copies from time to time. If you want real longevity there might be other options, perhaps something a little more up to date technologically - etchings on diamonds, perhaps?).
When people cite constitutional amendments, what they are doing is reminding authority (not just the acting authority, but that of anyone who will listen and cares, governors and governed alike, which is the greatest authority of all when roused) just exactly what it agreed it would and would not do for them or against them.
This works as long as people value consistency, fairness and honesty in their government; proving that a government has acted inconsistently with its agreed purpose and principles should, in any healthy society, be a death-blow for that government. If a government is even once shown to be inconsistent in carrying out its purpose, it cannot be trusted. At all.
Remember Orwell's "Memory Hole"? This is precisely what he was on about.
