There's nothing as unsettling as the realisation that something you thought you owned belonged to somebody else all along. It's true of a whole load of things -- cars that the previous owner didn't finish paying for, that second-hand stereo liberated by the local tealeaf and flogged through eBay, the present from a friend that wasn't his to give. Such things belong firmly in the class of vague worries we don't like to think about because they're too difficult to guard against and besides, we'd never get any sleep.
But such things happen. Ask the makers of digital cameras, scanners and picture editing programs, who have just been told to cough up or else. The wielder of these threats, Forgent Networks, is waving a wad of patents that it claims covers aspects of the JPEG picture format -- a format that until now was accepted as freely usable. It's an international open standard of some maturity: it's hard to think of something safer. But then, you'd have said the same of the humble hyperlink before BT decided to lay claim to the idea: it doesn't look as if BT will win that one, and it's not clear whether the Forgent claim will stand up to scrutiny. But it'll be an expensive discovery in both cases, whoever wins.
The real question is -- is it possible to write any new software these days that you know won't hit patent problems later? Imagine if the same situation held for the written word. For something to be worth reading, it needs to be novel -- either with new facts, or drawing together old ideas in an interesting way. You may have already thought about the similarities between publishing English prose and publishing software, but I'm betting it's worth putting into print here. It's not a perfect analogy, but it has its virtues.
So far, so good. But if the same laws applied to both English and software, my employer couldn't publish the previous paragraph without checking whether someone had already patented the idea of using analogies between software programming and writing English. And, since it's not possible to see the details of patents pending under US law, even a full check wouldn't prevent future problems.
This would leave publishers with a tricky choice: either publish and be prepared to absorb the cost of any subsequent licence claim or court case, or not publish at all. Even if a publisher adopts the Wellington strategy and loudly declaims "Publish and be damned", you can bet your bottom Enron share that the potential liabilities had better appear on the balance sheet somewhere.