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On the Internet, nobody knows you’re a dog, according to the famous New Yorker cartoon. But, canine or human, your opinion still matters in the courtroom.

A federal district judge from Tampa earlier this month relied on an anonymous Yelp posting as key evidence in a ruling on a business dispute between rival health clubs.

YouFit, a five-year-old chain of health clubs based in Florida, brought a trademark infringement complaint against former franchisees who operate health clubs under the name “Fit U.”

Judge James Whittemore granted YouFit a preliminary injunction, ordering the defendants to stop calling themselves Fit U.

Lawyers for YouFit and the defendants, the operators of “Fit U,” were not immediately available for comment.

What’s interesting here is that Mr. Whittemore cited a Yelp review as evidence of potential consumer confusion, an important factor in trademark litigation.

The judge quotes a Yelp reviewer called Scott R., who wrote:

I am soo confused. I was a member at Youfit in [Arizona] and when I moved back to [California] I saw this place by my house and thought great my gym is here! When I went into the gym, I realized it was called Fit U. They use the same basic color scheme on their sign and the motto seemed the same. When I asked the girl at the desk, … [she] said her owner created this brand. I said what are you [sic] rates? Seemed very similar to me as when I was a member at Youfit. Very confusing and a big let down.

Said Mr. Whittemore:

While these anonymous posts are not conclusive evidence of actual confusion, they are indicative of potential consumer confusion. This factor therefore weighs in favor of a finding of likelihood of confusion.

What do we know about Scott R.? He (assuming gender) listed Concord, Calif. as his location. His Yelp profile page says he registered the account last year and has posted just that one review. That’s about it.

Attorneys for the defense argued that a magistrate judge who earlier recommended that the injunction motion be granted assigned too much importance to the Yelp posts.

On the question of how we know that Scott R. is an actual confused consumer — and not a dog — behind the keyboard, Mr. Whittemore does not say.

“With no analysis as to why, the court found the Yelp posting appropriate to consider at this stage of the case,” writes Evan Brown, an intellectual property attorney in Chicago.

Mr. Brown adds: “The court’s opinion does not address what one might see as the real problem with the Yelp evidence — its authenticity.”