More generally, our results suggest that narrowly defined intellectual property – in the form of copyright – can encourage innovation. This finding contrasts with historical evidence on more broadly defined intellectual property rights such as patents, which suggests that policies that weaken patents encourage innovation, while policies that strengthen patents discourage innovation (Moser 2013). For example, my analyses of 19th century innovations indicate that the adoption of patent laws may affect the direction, but not the level of creative work (Moser 2005).
Intuitively, the narrow scope of copyright, which protects an individual expression of a work, prevents a key problem with patents. When patent rights are broad and their boundaries are poorly defined, innovators are at risk of unintentionally infringing on existing intellectual property, and patent examiners may issue overlapping patents for the same invention. These characteristics of patent laws increase the risks of litigation and discourage innovation. Comparison of patents and copyright suggests that intellectual property policies that reduce the breadth of patents (for example, by disallowing patents for abstract ideas) can encourage innovation.