>it's fundamentally impossible to know that a thing is unencumbered One noteworthy exception, which plays a much bigger role in slower-moving industries, is th

>it's fundamentally impossible to know that a thing is unencumbered One noteworthy exception, which plays a much bigger role in slower-moving industries, is that an exact copy of something sold over more time than the pendency of any patent in existence (mostly less than 23-24 years) is clear. But the larger point holds. Comparing patent claims to products and prior art is hard and expensive.