Evan Schuman's StorefrontBacktalk

Oracle has jumped into an E-Commerce patent fight with guns blazing, asking a court to invalidate patents that have been used to sue Walgreens, Best Buy, Sam’s Club, CVS and other large chains in the past year. The lawsuit, filed on June 1, says Oracle’s customers are being sued or threatened for using its Web-commerce products, including its live-chat support feature.

What’s unusual isn’t that Oracle is stepping up to defend its customers. It’s how the database giant is doing that: by using its initial court filing to list dozens of previous patents that, Oracle says, prove the Patents-in-Suit should never have been issued.

The Oracle complaint, filed in federal court in Wisconsin, is against Lodsys, a so called “patent troll” that last year sued Sam’s Club, Best Buy, Adidas, CVS, The Container Store and Vitamin Shoppe for allegedly violating its patents by doing online surveys. The same patents were used by Lodsys last month to sue Walgreens and REI for using Oracle’s chat feature and to send threatening letters to what Oracle calls “dozens of Oracle customers.”

(If Lodsys’ name sounds familiar, it’s also the company that sold a patent license to Apple for M-Commerce on the iPhone, and then sued 10 small iPhone app developers last year for using that feature. Other online businesses ranging from Smucker’s to the New York Times have also been threatened or sued by Lodsys. Yes, it’s the same four patents: U.S. Patent No. 5,999,908, No. 7,133,834, No. 7,222,078 and No. 7,620,565.)

Of that list of retailers, at least two are off the hook. Last year, just before its customers Best Buy and Adidas were sued, Web survey company ForeSee sued Lodsys, claiming the patents were invalid. That lawsuit was settled out of court in November, with all of ForeSee’s customers cleared of liability.

That brings us back to Oracle, whose complaint against Lodsys looks a lot like ForeSee’s and other previous lawsuits in which vendors asked the court to declare Lodsys’ patents invalid, even though the vendors themselves hadn’t been sued.

But those previous complaints just claimed the Lodsys patents weren’t valid. Oracle took the additional step of specifically naming 35 U.S. patents and five Japanese patents that predate the Lodsys patent claims. If the court agrees that some of those patents are “prior art” for the Lodsys patents, some or all of the patent claims could be invalidated.

That’s highly unusual. Lawsuits challenging patents are hard enough to win. There’s a presumption that the patents are valid—after all, the Patent Office has already spent years vetting them before they’re issued. Showing all your patent-busting cards at the beginning of the first round is just giving the other side more time to poke holes in your argument. And 40 separate patents represent a lot of cards to show.

And it may not end there.