Users voluntary register on an independant ID registry whereby anyone on it is in a web of trust that builds up and dissolves temporarily. They register to have their ID implanted or even just worn on the body as a label - on a piece of jewellery for example. All this contains is a tag. We create a binding legal place for this piece of hardware to exist so that research in this area can never be held privately by an organisation. All uses must be available and accessible to all users of the system. Encryption programs would be the most obvious possibilities, or monitoring systems, even trust networks identifying where someone is at any one time (to allow tracking of an elderly person in a house or for artistic theatre purposes).
The reason is not some underlying commercial gain or future takeover by some archevil nemesis. It's just doing it ourselves before they do it to us anyway.