Discovery v. Amazon: A lawsuit with legs

As described in an article by CNET's Greg Sandoval yesterday ("Discovery hits Amazon with Kindle patent suit"), the parent company of the Discovery Channel (Discovery Communications) has filed a lawsuit against Amazon.com, claiming that the Internet retailer's Kindle e-book reader infringes Discovery's U.S. patent 7,298,851, titled "Electronic book security and copyright protection system".

I read through this patent in some detail, and honestly, it looks formidable. It was filed in 1999 as a "continuation in part" from patent applications dating back to 1992. Among the prior-art disclosures listed are 52 U.S. patents or applications, 34 foreign patents or applications, and 15 nonpatent publications. It has 171 claims, three of which are independent. Those are all signs of a strong patent.

I'm inclined to believe that the eight years of pendency and all that prior art is evidence of a mighty battle between the inventors and the U.S. Patent and Trademark Office--a battle that Discovery Communications eventually won when the patent was granted.

Claim 1 in the Discovery patent is long but reasonably straightforward:

1. A method for encrypting, sending, and receiving electronic books upon demand, comprising: creating a list of titles of available electronic books; transmitting the list of titles of available electronic books; selecting a title from the transmitted list of titles; communicating the selected title to an electronic book source; supplying a selected electronic book corresponding to the selected title to be encrypted; supplying an encryption key; encrypting the selected electronic book using the encryption key; supplying the encrypted selected electronic book; supplying a decryption key; and decrypting the encrypted selected electronic book using the decryption key.

For this claim to cover the Kindle, each step in this process has to be performed by the Kindle, Amazon's servers, or the Kindle's user (as appropriate). There are many steps, but most of them are necessary, or implied by other steps, so the total complexity of this claim isn't really that bad.

I could quibble about some of this claim language, but it does seem to describe the process used by Amazon and other e-book sellers. If that's true (and only Amazon can really say for sure, at this point), Amazon's best hope to invalidate this claim may be to find some as-yet unnoticed e-commerce patent or publication that describes the same process, as applied to some other kind of electronic content, then base an obviousness claim on that, uh, discovery.

The real issue here isn't so much whether this method is or isn't obvious; I think it is. It's that the patent has been examined in light of so much prior art that it has acquired a reasonable presumption of novelty and nonobviousness. Amazon would find it very difficult to say anything in the listed prior art invalidates this patent because the Patent Office has already said it doesn't.

The vast majority of the dependent claims built on Claim 1 are not relevant, and if Claim 1 were invalidated, I doubt that they'd matter. Claims 96 and 129, the other independent claims, are weaker than Claim 1, and it seems less likely to me that they are being infringed, but as always, courts can make unexpected decisions.

I bet we'll be hearing a lot more about this suit because it's going to affect a lot of companies that haven't actually been sued yet, including at least Adobe Systems and Sony, both which seem to use something like this process. Sony sells e-books for its Reader, and Adobe's Digital Editions software may be covered by this patent.

And I'm sure that there must be other companies that should be concerned, though the precise manner in which e-books are sold is crucial in this case, and different companies have different implementations.

One of my quibbles with the patent's Claim 1 is that it doesn't describe the situation in which the e-book itself is pre-encrypted, and the only thing that happens at the time of purchase is encrypting the book's decryption key. That distinction could become a major issue in the lawsuit.

Another quibble is that the claim seems to require that the whole e-book be encrypted with a single key, which may not always be the case. The patent's specification does mention cases in which only a portion of the book is encrypted or decrypted; these mentions, though minor, may also prove significant.

Comments on Sandoval's article point out that e-books and e-book readers were on the market before the 1999 filing date of the Discovery patent application, but that doesn't mean that they used any of the methods described in the patent's claims. For example, they may not have encrypted the e-books. It's also possible that some of those older patent applications, going back to 1992, might establish an earlier priority date for the Discovery patent's claims, though that's less likely.

At any rate, I'll be keeping my eye on this one.