Optimal patent breadth in a horizontal innovation growth model

Patenting and licensing are introduced into the lab-equipment horizontal innovation model of endogenous growth. Patent length is not deterministic, in that patent holders' market power will collapse if and only if their patented goods get successfully imitated. The model is solved in an exact fashion. Consideration of static and dynamic inefficiencies shows that optimal intellectual property rights protection entails maximal patent length, but nonmaximal patent breadth. By fixing a lower patent breadth level, government is able to trade off a modest negative long-term effect on growth for a substantial positive short-term effect on consumption. A third potential source of inefficiency, reputational, is also considered.