The Seigenthaler Wikipedia hoax

That John Seigenthaler Sr. — journalist, editor of The Tennessean, and administrative assistant to Attorney General Robert Kennedy — was 'thought to have been directly involved in the Kennedy assassinations of both John and his brother, Bobby', and had lived in the Soviet Union for thirteen years.

The text was added anonymously to Wikipedia in May 2005 by Brian Chase, an operations manager at a Nashville delivery company, who later said he had written it to amuse a co-worker and had believed Wikipedia was a joke site rather than a reference work anyone consulted. It survived for four months, propagating to mirror sites that republish Wikipedia content automatically. Seigenthaler learned of it in September and wrote about it in USA Today in November 2005, describing his inability to identify the author or get the copies removed.

The response reshaped the reference work itself. Wikipedia restricted article creation to registered accounts within days, and the incident is the proximate cause of its biographies of living persons policy, which requires immediate removal of unsourced contentious material about a living person. That policy is now the reason a comparable insertion is measured in minutes rather than months. Seigenthaler, who had founded a First Amendment centre, spent his remaining years arguing against liability rules that would have solved his problem by making open reference works impossible — a position considerably more careful than the one his own experience invited.