Abstract
A strong tradition in economic history, which relies primarily on qualitative evidence and statistical correlations, has emphasized the importance of patents as a primary driver of innovation. Recent improvements in empirical methodology—through the creation of new datasets and advances in identification—have produced research that challenges this traditional view. The findings of this literature provide a more nuanced view of the effects of intellectual property and suggest that when patent rights have been too broad or too strong, they have actually discouraged innovation. This review summarizes the major results from this research and presents open questions.