Intellectual property rights in a quality-ladder model with persistent leadership

This article analyzes the effects of intellectual property rights in a quality-ladder model in which incumbent firms preemptively innovate in order to keep their position of leadership. Unlike in models with leapfrogging, granting non-expiring forward protection reduces the rate of innovation and imposing a non-obviousness requirement reduces R&D spending. It is shown that full protection against imitation, granted independently of the size of the lead, maximizes the average innovation rate.