Have you ever sat in an airplane, typing on your laptop, when the darn thing crashes for the one-millionth time? Have you ever then thought about how the airplane you are sitting in is controlled by software, too--the technical term being "fly by wire"--and then started sweating uncontrollably? Software controls not only air traffic but plenty of other safety-critical technologies: the tightrope walk of controlling the chain reaction of radioactive elements in nuclear power plants; the navigation and activation of missiles;3 the moves and cutting-depth of a surgical laser when correcting eye-sights; the list goes on... With such reliance on software, malfunction due to errors in the program code becomes unacceptable. Software patents help heighten the standard by supporting the re-use of the code of established and tested systems.
Michael Guntersdorfer, Software Patents: What One-Click Buy and Safe Air Travel Have in Common, 1 Duke Law & Technology Review 1-7 (2002)