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The fashion industry has its own Sherlock Holmes, and thanks to him, one of the Internet’s largest traffickers in counterfeit goods is going to pay.

And that Sherlock is a PI from Plano, Texas. Named Holmes.

Rob Holmes is a private investigator and owner of IPCybercrime in Plano, and he blew the lid on one of the world’s biggest counterfeit goods sales sites with a year-long undercover operation. In doing so, he may have helped give brands a new legal tool in their attempt to stamp out billions of dollars in sales lost to counterfeiting each year.

In an interview with VentureBeat, Holmes said his work helped unearth evidence that the Pakistani e-commerce vendor TradeKey helped enable wholesale trading of thousands of counterfeit goods over the Internet by setting up a “virtual swap meet” where vendors could sell fake goods with impunity. A federal judge ruled on Oct. 8 that TradeKey had violated copyright law and contributed to the counterfeiting of goods made by companies, including Holmes’ client, Richemont, the owner of six luxury fashion brands including Mont Blanc-Simplo, Cartier, Chloe, Alfred Dunhill, Officine Panerai, and Lange Uhren. Holmes said he found thousands of cases of large-scale counterfeit listings during his undercover work.

TradeKey counterfeit listings.

Above: TradeKey counterfeit listings.

Image Credit: Court filing

Holmes told us how, at the request of Richemont’s lawyers, he organized the undercover investigation with luxury brand company’s legal team as it pursued TradeKey, a site that had more than 5 million members at the time of the investigation. The tale is a case study in how big brands are going after shadowy counterfeiters and how tricky it can be to collect evidence that will bring those counterfeiters down.

The case could set a new legal precedent, since an earlier ruling in 2010 put the burden of stamping out counterfeiting on e-commerce sites on the brand claiming to be a victim. In the case of Tiffany v. eBay, the U.S. courts ruled that eBay was not responsible for policing its market for counterfeits sold by third parties. That decision put the burden on brands to provide proof to eBay if they wanted it to take down a counterfeit sale.

But in the TradeKey case, the evidence of counterfeiting was so widespread throughout the site that a federal judge ruled that TradeKey was in fact responsible for curbing counterfeit sales. That ruling by U.S. District Court judge Gary Allen Feess in Los Angeles is the latest result of a one-year investigation and three-year legal case against TradeKey. The judge found that TradeKey had “actively promoted and facilitated the sale” of counterfeits. He ordered it to monitor its sales.

“This is the first case that holds an online marketplace liable for contributing to counterfeiting,” Holmes said in an interview with VentureBeat. “And they were the No. 1 counterfeiting site in the world. This was the big, bad one.”

It’s hard to verify if TradeKey was the biggest counterfeiting site, but Holmes does work for about 50 brands, and the lawyer for Richemont agrees it was a big one.

“We believe the case is groundbreaking in the magnitude of the counterfeiting on TradeKey.com,” said Susan Kayser, legal counsel for Richemont at the law firm Jones Day, in an interview. “Rob Holmes’ investigation was essential to the case. The court relied heavily on the investigation’s findings in its ruling.”

TradeKey’s attorney, Erik Syverson of Miller Barondess, said in an e-mail, “We completely disagree with the court’s ruling, factual findings and application of the law, particularly with respect to contributory liability principles. Followed to its logical conclusion, this ruling requires web sites that permit user-generated advertising to proactively screen for infringing or counterfeit items listed for sale. That is not the law.”

He added, “The law has always required that trademark owners perform such a function. Furthermore, the ruling impermissibly restricts the legal use of trademarks in meta data and adwords, even by third parties not connected to this lawsuit. For example, under this ruling, I cannot list for sale on my client’s website my own collection of authentic Mont Blanc pens, or even mention Mont Blanc for comparative advertising purposes.”

He said TradeKey is considering its options. He did not elaborate.