TheLegalImplicationsOfWikis

Suppose I were to defame JimboWales, e.g., saying that he is an insensitive clod, overly fond of sheep, and a boozing stinker (or a stinking boozer). Could anyone bring a defamation lawsuit against the owner of Wikipedia's server (which, it so happens, is JimboWales), against the defamer of JimboWales, or against anyone else?