One feature of the European patent system that is heavily criticized nowadays is related to its complex fragmentation and the induced cost burden for applicants. Once a patent is granted by the EPO, the assignee must validate (and often translate) it and pay the renewal fees to keep it in force...

This paper reviews the economic literature on the role of fees in patent systems. Two main research questions are usually addressed: the impact of patent fees on the behavior of applicants and the question of optimal fees. Studies in the former group confirm that a range of fees affect the...