Software patents have grown rapidly in number and now comprise 15% of all patents. They are acquired primarily by large manufacturing firms in industries known for strategic patenting; only 5% belong to software publishers. The very large increase in software patent propensity over time is not...

U.S. legal changes have made it easier to obtain patents on inventions that use software. Software patents have grown rapidly and now comprise 15 percent of all patents. They are acquired primarily by large manufacturing firms in industries known for strategic patenting; only 5 percent belong to...

Patent race models assume that an innovator wins the only patent covering a product. But when technologies are complex, this property right is defective: ownership of a product's technology is shared, not exclusive. In that case I show that if patent standards are low, firms build "thickets" of...