Maintaining historical data in a git repo

As part of a public project to open-source the Israeli law code, we are looking into ways of represent such data in a git repository.

The main challenge is to represent historical data _in a semantically correct way_ within a git repository, while having the ability to change data that has occurred in the past. For example, we might have revisions B and C of a certain legal document, commit to repo, and at a later time want to add revision A to the proper place in the git commit tree (probably with rebasing or replacing). Allowing decentralization and updates is a major requirement.

We're trying to map out the various pros and cons of the different options of maintaining such a repo. Has anyone ever attempted something like this? Are there any projects that build on the git plumbing which provide wrapper APIs to handle historic data?

We really could use any reference or advice we can get on this subject.

Thanks,

-- Yuval Adam http://y3xz.com