What is Wex?
WEX is a collaboratively-edited legal dictionary and encyclopedia. It is intended for a broad audience of people, ranging from lawyers to law students to people who have no experience with the 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. (See Why bother?.)
Who can contribute?
Potentially, anyone qualified to do so. We limit access to the Wex authoring apparatus as a way to make sure that our high-quality collection remains free of vandalism and misinformation. 
Why not just contribute law material to Wikipedia?
Excellent question! In time, we may offer our material to Wikipedia, or may otherwise merge our efforts with theirs. In the short term, we (the LII) want to retain more control over what appears here (see Why not Wikipedia?.) Once we have a better idea of what stresses and strains are involved in running such a system, we may consider moving.
Who runs Wex?
Wex is a product of the Legal Information Institute at the Cornell Law School, a pre-eminent source of legal information. Much of its current content is based on (or directly incorporates) material developed by the LII for use on the its website.

See also