Two-Stage Patent Races and Patent Policy
在两阶段专利竞赛框架下分析最优前向专利保护程度，比较三种专利制度对第二阶段创新的投资激励和社会福利影响，发现强前向保护在特定条件下效率降低。
I analyze the optimal degree of forward patent protection in a two-stage patent race framework. I compare three patent regimes, as the second innovation may be unpatentable and infringing (UI), patentable and infringing (PI), or patentable and not infringing (PN). Forward protection is highest in regime UI and lowest in regime PN. I identify a fundamental inefficiency affecting regime UI, namely that it always leads to underinvestment in the second innovation, and I note various determinants of the welfare ranking of the regimes. Specifically, strong forward protection becomes less attractive as the relative profitability of the first innovation increases and the relative difficulty of obtaining it decreases.