I have a couple of examples from my personal experience, neither earth-shattering, but when you consider X million engineers running into similar issues, the cumulative tax on innovation is pretty large.<p>Working on F1 '98, we had to scrap a whole training mode where you'd see your time compared to previous laps because lawyers were concerned it overlapped with the Atari 'ghost car' patent:<p><a href="http://kotaku.com/270035/patents-are-interesting-ghost-mode" rel="nofollow">http://kotaku.com/270035/patents-are-interesting-ghost-mode</a><p>We spent a lot of time and energy trying to work around this, we weren't showing any kind of ghost car, just a time indication, but apparently the patent was broad enough to cover any kind of comparison.<p>The second was a patent on controlling any kind of video effect based on a sound input(!). This severely constrained what we could do on a major video-processing package, forcing us to avoid some features. They tried to extort independent developers out of a lot of cash, despite being a painfully obvious idea that had been around for decades before the patent was filed:<p><a href="http://www.trapcode.com/US_SK_advisory.html" rel="nofollow">http://www.trapcode.com/US_SK_advisory.html</a>