The Signpost covered the beginning of this trend in a UK court case in 2006, and further cases in 2007. The latter was prompted by a New York Times article that year by Noam Cohen, a frequent contributor to its Wikipedia-related stories. At the time, Cohen reported that more than 100 American court cases had cited Wikipedia, including 13 from the federal appeals courts (as distinct from American state appeals courts, within each of the states). Why did the judiciary choose to cite Wikipedia? Cohen quoted Stephen Gillers of the New York University Law School as saying that the most critical factor is public acceptance, including acceptance by the litigants: "A judge should not use Wikipedia when the public is not prepared to accept it as authority." Cohen elaborated:
For now, Professor Gillers said, Wikipedia is best used for 'soft facts' that are not central to the reasoning of a decision. All of which leads to the question, if a fact isn’t central to a judge’s ruling, why include it? "Because you want your opinion to be readable," said Professor Gillers. "You want to apply context. Judges will try to set the stage. There are background facts. You don’t have to include them. They are not determinative. But they help the reader appreciate the context." He added, "The higher the court the more you want to do it. Why do judges cite Shakespeare or Kafka?"
By 2008, the number of American court cases that cited Wikipedia had quadrupled, prompting commentary from Professor Lee Peoples, who concluded in the Yale Journal of Law & Technology that much caution is needed in citing Wikipedia because of web-page fluidity and the multiple issues inherent in a page freely editable by anyone; but in his view, it could be acceptable in "in some limited situations for defining slang terms and for getting a sense of a term's common usage." (more below)
The practice has continued. This week, the Utah Court of Appeals issued a 12-page ruling in Fire Insurance Exchange v. Robert Allen Oltmanns and Brady Blackner—which included a five-page concurring opinion from Judge J. Frederic Voros, Jr. specifically dedicated to the issue of citing Wikipedia in law decisions.
Voros quoted extensively from Peoples' 2008 study. Voros recognized the problem of Wikipedia's fluidity and quoted Peoples' study: without "a date- and time-specific citation, researchers who pull up a Wikipedia entry cited in a judicial opinion will never be absolutely certain they are viewing the entry as it existed when the judge viewed it. ... This may ultimately lead to uncertainty and instability in the law." He also touched on the divide in the judicial sector over whether to cite Wikipedia or not, saying that "citing Wikipedia is as controversial as it is common", before moving into a justification for a significant citation to Wikipedia in this case.
Voros relied heavily on Peoples in crafting this portion of his opinion, noting Peoples' "bright line rules" for not citing Wikipedia in a judicial opinion, including technical or scientific terminology. He based his defense of the citation in the specific definition needed—the common meaning of "jet ski". Fire Insurance Exchange's (FIE's) insurance policy noted that it would not cover injuries that result from "the ownership, maintenance, use, loading or unloading of aircraft, motor vehicles, jet skis and jet sleds", or various specified types of watercraft.
So the lawsuit alleged that FIE did not have to compensate Oltmann and Blackner for the injuries they suffered on their personal watercraft because "jet ski" applied to any watercraft of that type. Oltmann and Blackner disagreed. Wikipedia enters the picture when "vernacular or colloquial is key to the resolution of a case"; the judges found that "Wikipedia is tough to beat" in this area. However, this was set against a scenario where a smart individual would want to "avoid a surgeon who bases his or her understanding of complicated medical procedures on an online source whose contributors range from expert scholars to internet trolls."
Voros went deeper, saying that Peoples' endorsement of "turn[ing] to Wikipedia entries for evidence of the common usage or ordinary and plain meaning of a contract term", along with similar cases that cited Wikipedia, is proof enough that a Wikipedia citation is appropriate: "Whatever its shortcomings in other contexts, for this task, an open-source encyclopedia with many editors and millions of readers seems just the ticket."