If you hang around geeks a lot, and heard the phrase "software patents" uttered in their presence, you'll have already experienced the barrage of invective that tends to result. What you may not have heard -- or may not have understood -- is why software patents are such a bad thing. Richard Stallman is writing about this issue in the Guardian today. But I think his case could be made more clearly:

Software patents are not the same as copyright. Copyright takes a work of art and says that you cannot copy it without the author's permission. You also cannot make a derivative work based on that art without the author's permission. Whether or not you're a fan of copyright (I am, although I have some reservations), the definition where copyright begins and ends is relatively clear-cut. George Lucas can sue you if your story is about X-Wings piloted by wookies, but he cannot sue you if your story is about spaceships piloted by big hairy apes.

With software patents, that's no longer true. Lucas could sue you for a story about apes piloting spaceships. He could sue you if your story featured swords that glow. He could even sue you if your story featured spaceships that travel faster than light, assuming one of the hundreds of authors who wrote about this before him hadn't patented it already.

Copyrights prevent you using somebody else's idea and work. Patents prevent you from using a similar idea, even if all the work is your own.

All of human invention, in fact all human culture, is about creating new ideas based on combinations of older ideas, since long before Newton claimed his work was merely standing on the shoulders of giants. This fundamental principle of the process of invention is explicitly blocked by software patents, which allow you to prevent other people writing software which has, for example, a progress bar, or an "add bookmark" button. Patents are no less than an attack on the fundamental principles of social and technological development.

So if patents are so horrible, why did we ever come up with them in the first place? The original purpose of patents certainly had a noble goal:

A patent is a bargain between the State and an inventor. In return for the inventor describing the invention to the public – for the advancement of science and technology – the State rewards the inventor with a limited monopoly that will prevent unauthorised commercial use of the invention.

Patents were supposed to be extremely technical documents that explained exactly how an invention worked, to the point where you could build one of your own. They were supposed to describe extremely technical things, like the gear mechanism on a combine harvester, or the design of circuits on a microchip -- stuff that you couldn't gather just by using the device or seeing it in action. The idea was that after the monopoly was up, everybody would be able to make these formerly-patented devices for free. They were supposed to promote technical advancement, not hold it back.

Needless to say, this is not true of software patents. Amazon has a patent on buying items with a single mouse-click: do we need a patent application to tell us how that works? Instead, software patents are used as a big stick by companies with lots of lawyers to scare other companies out of competing with them, by essentially patenting every aspect of their business model until it's impossible to be in the same business as them without breaking the law. It's a truly perverse abuse of the law.

Software patents do no good, and do lots of harm. They don't currently exist in the EU. Make sure that stays the case.