In a recent opinion, United States v. Lawson, the Fourth Circuit had this to say about Wikipedia's reliability:
Given the open-access nature of Wikipedia, the danger in relying on a Wikipedia entry is obvious and real. As the "About Wikipedia" material aptly observes, "[a]llowing anyone to edit Wikipedia means that it is more easily vandalized or susceptible to unchecked information." Id. Further, Wikipedia aptly recognizes that it "is written largely by amateurs." Id.