Many noted Judges rely on Wikipedia as authority including defining “Blazing Saddles” and “happy hour,” but the US Supreme Court has not yet accepted Wikipedia as authority. The New York Times reported in 2007 that Judge Richard A. Posner of the United States Court of Appeals for the Seventh Circuit and well-known blogger, in Chicago claimed that “Wikipedia is a terrific resource.” Judge Posner went to say:
Partly because it so convenient, it often has been updated recently and is very accurate…It wouldn’t be right to use it in a critical issue. If the safety of a product is at issue, you wouldn’t look it up in Wikipedia.
However in a recent ruling of US v Larson, US 4th Circuit Court of Appeals Judge Barbara Milano Keenan overturned a jury conviction for violating, and conspiring to violate, the animal fighting prohibition of the Animal Welfare Act, 7 U.S.C. § 2156(a) (the animal fighting statute) because Juror 177 searched Wikipedia for the definition of "sponsor," one of the elements of the offense under the animal fighting statute. The Wikipedia search was determined to be juror misconduct since Juror 177 relied definitions not provided in court, but Judge Keenan also pointed out that definitions on Wikipedia are subject to change by public edits and therefore Wikipedia is not reliable. Which is an interesting position since Judge Posner feels the opposite.
It seems to me that Wikipedia is a reliable authority for many lawsuits and will be more widely accepted in the future.