As a former patent examiner, I don’t see why a wikipedia can’t be used as prior art.  Every change to a wiki article is documented by substance and date, so there doesn’t seem to be a “constantly changing” problem. That is, even if it changed, the old version is still available as well as its date of publication.  If a wiki article included information sufficient to render an application anticipated or obvious at a certain date and the information from that date can be retrieved, I don’t see the problem.  To address Aharonian’s concerns, even if things in the article aren’t true, that doesn’t disqualify them from being prior art as long as they are enabling. Yes, from a legal point of view, I wouldn’t rely on a wiki cite in a Supreme Court brief, but that doesn’t refute the argument that something was indeed published on an established date, and is still available, that renders an invention anticipated or obvious.  I just don’t see why wikipedia was singled out among all sources, especially in view of the fact that an article from *any other website* can be used as prior art without explicit PTO condemnation. At least wikipedia is reviewed by a community, whereas each cult leader who claims to have invented a time-warping spaceship can publish anything he wants without review (I’ve actually used one of these sites in a rejection before).