International audienceThe contemporary tensions between patents and competition no longer reside in the traditional trade-off between the exclusionary right given to an inventor to encourage innovation, and the welfare loss induced by the market power associated to this right. They rather result from three important distortions of the patent system that create conflicts between patents and competition on the product market, the technology market, and the innovation market. The first distortion is related to the existence of dubious or weak patents: too many patents are granted to applications of bad quality according to the patentability criteria. This increases the uncertainty attached to patents, reduces the credibility of the system and ...