Have you heard the one about the dog who walked into a rabbinical court?

Here's how the BBC reported it: A pooch made its way into a beth din in Jerusalem's ultra-Orthodox neighborhood of Mea Shearim. One of the judges, believing the dog to be the reincarnation of a now-deceased lawyer whom the court had cursed some two decades earlier, sentenced the dog to death by stoning, and ordered that the sentence be carried out by children. The dog escaped before the sentence could be carried out. Dog-lovers have filed a complaint against the court.

This story has it all. Religious zealots! Animal rights activists! Blood libel! Children! Ingredients that tend to nourish the more primitive regions of our minds and starve the rest. Best of all, it runs under 200 words and stars a dog.

The story's only deficiency is that it comes up short in the being-factually-true department.

As it turns out, the BBC, along with Agence France Presse, Time Magazine, and a handful other news outlets got the story from Ynet, the website for Yediot Ahronot, Israel's second-largest newspaper. Ynet's story says that the head of the court denied that such an incident had taken place, a detail that was left out of the original BBC, Time, and AFP stories. The paper is also alone in noting that there was no official ruling, just a rabbi telling kids to throw rocks at a dog.

Ynet didn't do any original reporting. They got the story from this in Behadrei Hadarim, a small Hebrew-language news outlet for Israel's ultra-Orthodox community. The Bhadrei Hadarim's reports that it got the story from someone who was present, but it doesn't bother to give that person's name.

Israel's third-largest paper, which doesn't have an English edition, also ran the story. They subsequently ran an apology, noting what the court said actually happened: A dog walked into a courtroom, and someone called the dogcatcher.

How did a story get from a single, unattributed source in a community news outlet to appearing on some of the world's most respected news outlets, with apparently nobody making any attempts to verify it?

After all, it's not the first time this sort of thing has happened. Just a few weeks ago, The New York Times, CNN, The Guardian, BBC, Agence France Presse, and Reuters all reported the discovery of dozens of bodies buried on a farm outside Houston. It turns out that police were investigating a tip from a self-described psychic, who not surprisingly turned out to be completely wrong.

"In the frenzied first 30 minutes of activity, one news organization after another built its wrong reporting upon the wrong reporting of others – The Times citing Reuters citing 'local media' citing, in some cases, nobody," writes media critic Bob Garfield on Mashable.

Garfield has a point: Repeating what has been said by other news outlets doesn't create knowledge. It just remixes it, sometimes with heavy distortion and amplification.

As budgets and news cycles shrink, piggybacking on other people's reporting, however sketchy, becomes inevitable. When this is done without verification, errors become increasingly frequent. So while "rabbi stones dog" may not be a true story, it's a useful cautionary tale for journalists, and that includes us. After all, you know what they say about those who live in glass houses.