The ridicule and scorn caused by a legal threat intended to suppress information.
Named after Charles Carreon, a self-proclaimed "Internet lawyer" who came to Internet infamy by attempting to silence Matthew Inman a.k.a The Oatmeal who had spoken out over another website's copyright infringement and their refusal to take down the infringing material. The complaint led to a charity fundraiser (which Carreon also tried to shut down, without success) and several Internet denizens attacking him via email and phone and hacking his website. Carreon eventually filed a motion of dismissal, ending the case.
Not to be confused with the Streisand Effect
Whoa, that lawyer totally felt the Carreon Effect when he tried to silence that blogger who complained about his posts being copy pasted.