Wal-Mart, Macy's and KB Toys are among the companies that have sent cease-and-desist letters to BlackFriday.info, complaining that the site published sales circulars too early this year. The comparison shopping site SearchAllDeals.com, which linked to a circular by Sam's Club (owned by Wal-Mart), also received a takedown notice from Wal-Mart, as did the blog CrunchGear (which had picked up the sales information from BlackFriday.info.)

The retailers say the sites are violating their copyright and also exposing trade secrets. In a cease-and-desist letter posted on SearchAllDeals.com, Wal-Mart alleged that the circular was not intended for public consumption until the Monday before Thanksgiving.

"The circulars and advertisement, as well as related documents are, prior to their authorized release date of November 24, 2008, confidential and proprietary information of Wal-Mart," the company wrote to SearchAllDeals.com.

Despite the retailer complaints, attorneys say it's not clear that the stores have the law on their side. While companies can obtain a copyright for ads and circulars in their entirety, stores generally can't copyright factual information such as prices. And to prevail on a trade secret claim, the store would have to prove that it derived value by keeping the upcoming sales confidential.

Eric Goldman, director of the High Tech Law Institute at Santa Clara University, said a company could theoretically prove they were hurt by disclosure of the discounts by showing that customers held off on making purchases this week after learning via the leaked circular that an item would soon go on sale.

But, he said, the claim didn't seem solid. "In the end, I wouldn't say that a lawsuit over the republication of this information was a strong case," he said.

Electronic Frontier Foundation lawyer Corynne McSherry added that pursuing claims that upcoming discounts are "trade secrets" could generate bad publicity for retailers. "In a court of public opinion, especially in these economic times, it's not going to look good to say, 'We make a lot of money by not telling people that we're about to put stuff on sale,' " McSherry said.

Wal-Mart also alleged in its cease-and-desist letter that the information on the circular was inaccurate. If so, that seems to undercut the company's argument that trade secrets were compromised.

While complaints about coupon sites publishing Black Friday sales prematurely date back several years, only one dispute appears to have landed in court. That case was brought by the coupon site FatWallet, which sued retailers in 2003 for having issued cease-and-desist letters to the site. FatWallet asked a federal district court to declare that the stores had no valid copyright complaints.

Megan Gray, who represented FatWallet, said the court dismissed the complaint after the retailers said they did not intend to file a lawsuit against FatWallet.

This news story is important. I recommend that everyone read it.