International audiencePatents are probabilistic rights. We set up a multi-stage model in which choosing between patent and trade secrecy is affected by three parameters : the patent strength defined as the probability that the right is upheld by the court, the cost of imitating a patented innovation relative to the cost of imitating a secret innovation, and the innovation size defined as the magnitude of the cost reduction. The choice of the protection regime is the result of two effects: the damage effect evaluated under the unjust enrichment doctrine and the effect of market competition that occurs under the shadow of infringement. We find that large innovations are likely to be kept secret whereas small innovations are always patented. F...