A key component of XDI is the Link Contract. The Link Contract is a digitally signed document that specifies the details of the data sharing agreement between the owner and the consumer of a set of data. There is various network enforced aspects to the contract but there are also social aspects of the contract. Lets break it down a bit.
If you look up Contract in the dictionary you get something like:
An agreement between two or more parties, especially one that is written and is subject to a system of accountability.
In most cases the system of accountability is the legal system. While Link Contracts could be written to be legally binding, we are still a long way from digital signatures being broadly accepted, especially automated ones. It is my belief that we are going to be much better served grounding our accountability in a reputation system. A mechanism by which quantifiable feedback is routinely provided when transactions end (or fail to end). The reputation system will have to be subtle and flexible. If I say something bad about you that might have implications on you, me, your community and my community. If I go around bad mouthing people all the time people need to have the queues to stop listening to me. Or, am I the people’s advocate who goes around outing bad guys, so people assign a good reputation to my negative opinions… ah, so much to work out :-)