Chris Pratley gives a glimpse into Microsoft’s patenting story:
At Microsoft, we used to pay little attention to patents – we would just make new things, and that would be it. Then we started getting worried – other big competitors (much bigger than we were at the time) had been patenting their inventions for some years, and it made us vulnerable. One of these big companies could dig through their patent portfolio, find something close to what we had done, then sue us, and we would have to go through an elaborate defense and possibly lose. So Microsoft did what most big companies do, which is start to build what is called a “defensive” patent portfolio. So if a big company tried to sue us, we could find something in our portfolio they were afoul of, and counter-sue. In the cold war days, this strategy was called “mutual assured destruction”, and since it was intolerable for all parties to engage, it resulted in a state called “détente”, or “standoff”. This is what you see today for the most part in lots of industries.