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Can You Trust Wikipedia to Decide Your Courtroom Fate?

Should judges and lawyers rely on Wikipedia to guide court case decisions? Researchers devised a clever test to see if they do

Wired recently ran an article entitled “Wikipedia Articles Sway Some Legal Judgments.” The subtitle declared: “An experiment shows that overworked judges turn to the crowdsourced encyclopedia for guidance when making legal decisions.” Wired’s headline oversold the story but the topic is worth a close look.

Researchers at Maynooth University in Ireland, MIT, and New York’s Cornell University conducted a study to test whether Wikipedia articles about Irish court decisions affected judicial rulings in subsequent cases in Ireland. The researchers selected Irish Supreme Court decisions, analyzed them, and posted about 75 articles in Wikipedia describing those decisions. They wanted to see whether Irish courts were then using the Wikipedia articles when writing their own judicial opinions.

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In English, Irish, Canadian, American, and other British-influenced common-law based jurisdictions, courts treat prior published decisions of “higher courts” as controlling and/or persuasive guides to future decisions. The body of published precedents becomes a source of controlling law in the jurisdiction, related to but somewhat independent of written constitutions and statutes passed by legislatures.

A specific published decision becomes more influential when it is cited by later courts (and not reversed or overruled). Lawyers and judges typically cite decisions as “the law,” and more frequently cited decisions are more persuasive in common-law based courts. The Irish research project thus looked at how often the decisions were cited by Irish courts after the researchers had posted discussions of those decisions on Wikipedia. The more often cited, the more influential the cases might be in future judicial rulings.

In their open access paper, the researchers found

  1. “Cases with a Wikipedia article increased citations by about 20%, a statistically significant amount.” This finding, at minimum, suggests that judges, their law clerks, and lawyers writing legal briefs arguing positions, looked at Wikipedia and found those researchers’ articles about Irish precedents.
  2. The disproportionately higher rate of at which cases with Wikipedia entries were cited was found in “lower courts,” e.g., trial level or first appellate level courts. This finding suggests that very busy trial court judges especially would tap Wikipedia for suggestions to save research time.
  3. Many of the Irish court decisions citing the precedents profiled on Wikipedia contained linguistic “fingerprints” — suggesting that words, phrases, and concepts were taken from the Wikipedia articles themselves.

As a practicing appellate lawyer, I confess to sometimes using general Internet searches about arcane or unfamiliar concepts that lead me to law firm web page discussions or to Wikipedia articles on the subject. Typically, I’m looking to find an oft-cited statute or judicial precedent. Then I return to Westlaw or Lexis law-specific research tools to continue my research. Truly, the Irish study showing that Wikipedia articles helped other researchers isn’t surprising or concerning.

The courts’ using the Wikipedia article wording written by the researchers does point to judges using the articles’ language as a shortcut. Here, too, however, lawyers and judges will adopt language from other sources, legal and otherwise, when the phrasing is especially clear or helpful, to use in legal briefs and
opinions. If the legal analysis is sound, such wordsmithing is no cause for concern.

The time to worry is when judges treat Wikipedia articles as evidence of facts or accurate descriptions of legal principles.

Can Wikipedia Articles Provide Evidence?

In a court case, evidence can be defined succinctly, as in the California Evidence Code § 140: “testimony, writings, material objects, or other things presented to the senses that are offered to prove the existence or nonexistence of a fact.”

By that definition, Wikipedia articles can potentially provide evidence. They constitute “writings” that reflect what something said or thought. The question is whether the Wikipedia-sourced information is admissible as evidence for the judge or jury to consider. Assuming a particular fact is relevant, the fact must still pass other tests.

For example, a witness may ordinarily testify only to personal knowledge and beliefs based upon personal knowledge. An expert witness, sometimes called an opinion witness, may testify giving opinions on specialized knowledge if the witness is qualified “by knowledge, skill, experience, training, or education,” and the testimony is based upon sufficient facts and reliable principles and methods for the subject area.

Aren’t Wikipedia Articles Just Hearsay?

Hearsay, defined in simple terms, is a statement by a person orally or in writing, declaring what someone else (not in court) said was true. Hearsay may be relevant evidence but not admissible when it is something said or written by a person not in court, not under oath, and not subject to cross-examination. Every Wikipedia article is therefore hearsay. But not all hearsay is excluded, because there are many rules that allow hearsay to be admitted.

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It turns out that reference works and encyclopedia articles can be admitted in court, despite their being hearsay, if an expert testifies to their accuracy or the documents are otherwise sufficiently reliable and trustworthy, and the documents are perhaps the best source currently available for the fact in question.

Can Wikipedia Articles Provide Sufficiently Reliable and Trustworthy Evidence?

Rather candidly, Wikipedia’s operators admit that Wikipedia articles are neither reliable nor trustworthy. Consider the Wikipedia General Disclaimer:

Wikipedia is an online open-content collaborative encyclopedia; that is, a voluntary association of individuals and groups working to develop a common resource of human knowledge. The structure of the project allows anyone with an Internet connection to alter its content. (Emphasis added.)

Observe how the Disclaimer concedes that a Wikipedia reader does not know (and perhaps can never know) the identity of any writers who make statements in an article. None of the writers are under oath; they face no penalty for being wrong, malicious, or deceptive. Moreover, the writer(s) can be anyone on Earth, regardless of qualification, and they can be different every day. None of the writers are shown to have personal knowledge of the facts in the article. None will face cross-examination to flesh out errors, defects, omissions, or biases.

The Disclaimer goes on to warn:

Please be advised that nothing found here has necessarily been reviewed by people with the expertise required to provide you with complete, accurate or reliable information… Wikipedia cannot guarantee the validity of the information found here. The content of any given article may recently have been changed, vandalized, or altered by someone whose opinion does not correspond with the state of knowledge in the relevant fields. (Emphasis added.)

Here Wikipedia torpedoes any notion of considering an article as “expert” testimony or opinion. The Disclaimer tells the truth: Wikipedia articles can be incomplete, inaccurate, invalid, and unreliable. Nobody will necessarily ever correct them, and the reader won’t know. Additionally, the article content is not constant and is not protected against being “vandalized” or “altered by someone” who doesn’t know what they’re talking about.

Although there are exceptions to the rule against admitting hearsay in court, Wikipedia articles fail as evidence because they lack a personal knowledge basis provided by any identified human or comparable source, and they lack any indications of trustworthiness that might otherwise apply to a reference work.

Do U.S. Courts Admit and Consider Wikipedia Article Information?

It’s so easy to grab a factoid from Wikipedia. The search engines often place Wikipedia articles as high ranked responses to search queries. Lawyers and judges have cited Wikipedia articles a lot; for unquestioned facts, that may be fine.

But both scholars and courts criticize citing Wikipedia for anything important. The Texas Supreme Court in 2017 expressly disfavored Wikipedia as a fact source:

Of the many concerns expressed about Wikipedia use, lack of reliability is paramount and may often preclude its use as a source of authority in opinions. At the least, we find it unlikely Wikipedia could suffice as the sole source of authority on an issue of any significance to a case.

The U.S. federal Fifth Circuit and Eighth Circuit courts of appeal have squarely denounced using Wikipedia articles as cited sources in judicial opinions. A federal court in California and the federal Court of Claims both criticized Wikipedia-sourced evidence, highlighting the Wikipedia disclaimers, the general lack of reliability of the stated information, the unknown state of completeness of the article, the lack of oversight or detection of errors and omissions, the lack of reliable citations to other sources of the information, and perhaps most importantly:

[M]any articles commence their lives as partisan drafts and may be caught up in a heavily unbalanced viewpoint.

Wikipedia in Court: The Verdict

A federal district court in 2020 rejected Wikipedia information as evidence, quoting a 2008 article in the journal Trial saying:

Since when did a Web site that any Internet surfer can edit become an authoritative source by which law students could write passing papers, experts could provide credible testimony, lawyers could craft legal arguments, and judges could issue precedents?

The convenience of Wikipedia for quick searches via voice or keyboard input does not mean its information is accurate, reliable, or trustworthy. Wisely, many U.S. courts have tamed the impulse to resort to the Wikipedia shortcut. Some writers still push to elevate Wikipedia’s status as a truth source — hopefully the courts will never surrender to the notion of “democratic” truth posted by unknown wikiphiles.


You may also wish to read: Wikipedia’s bias meets a free-speech alternative. The famously free encyclopaedia’s pages on abortion, communism, and historical figures reveal a left-leaning bias. Wikipedia’s neutral point of view “is dead”, declares co-founder Larry Sanger, who is now launching a free-speech alternative.


Richard Stevens

Richard W. Stevens is a lawyer and author, and has written extensively on how code and software systems evidence intelligent design in biological systems. He holds a J.D. with high honors from the University of San Diego Law School and a computer science degree from UC San Diego. Richard has practiced civil and administrative law litigation in California and Washington D.C., taught legal research and writing at George Washington University and George Mason University law schools, and now specializes in writing dispositive motion and appellate briefs. He has authored or co-authored four books, and has written numerous articles and spoken on subjects including legal writing, economics, the Bill of Rights and Christian apologetics. His fifth book, Investigation Defense, is forthcoming.

Can You Trust Wikipedia to Decide Your Courtroom Fate?