Vincenzo Denicolò and Luigi Alberto Franzoni

We analyze optimal patent design when innovators can rely on secrecy to protect their innovations. Secrecy has no fixed term but does not preclude accidental disclosure nor independent creation by other inventors. We derive the optimal scope of the rights conferred to such second inventors, showing that if the patent life is set optimally, second inventors should be allowed to patent and to exclude first inventors who have relied on secrecy. We then identify conditions under which it is socially desirable to increase patent life as much as is necessary to induce first inventors to patent. The circumstances in which it is preferable that they rely on secrecy seem rather limited.