Here's a snippet from the FAQ:
What is Wex?Built on the MediaWiki platform, it's nice to see organizations like LII & Cornell embrace the technology and throw their weight behind this type of project. Wex looks very promising. Congratulations to all those involved in the project!
WEX is a collaboratively-edited legal dictionary and encyclopedia. It is intended for a broad audience of people we refer to as "law novices" -- which at one time or another describes practically everyone, even law students and lawyers entering new areas of law. No doubt purists will be quick to point out the differences between a dictionary and an encyclopedia. We deliberately blur the distinction, as we are interested in providing objective, useful material in a range of formats.
Who can contribute?
Potentially, anyone qualified to do so. We limit access to the Wex authoring apparatus as a way of ensuring that the quality of material here remains high, and free of vandalism of various kinds. If you're interested in becoming an author or editor, or if you want to know more about our selection criteria, take a look at the article on editorial contributions.
Why not just contribute law material to Wikipedia?
Excellent question. In time, we may offer our material to Wikipedia, or otherwise merge our efforts with theirs. In the short term, we (the LII) want to retain more control over what appears here. Once we have a better idea of what stresses and strains are involved in running such a system, we may consider moving.