Patent Policy and Costly Imitation
扩展了最优专利理论，考虑模仿成本，发现专利保护期越长，竞争对手越可能绕开专利，因此最优专利期应足够短以抑制模仿；当专利长度和宽度均可调整时，最优政策是宽专利（禁止模仿）配合调整专利期。
This article extends the theory of optimal patents to allow for costly imitation of patented innovations. With costly imitation, a rival's decision to imitate depends on the length of patent protection awarded to the patentee: the longer the patent life, the more likely it is that rivals will invent around the patented product. Extending patent life, therefore, may not provide the innovator with increased incentives to research or to patent the innovation. In this case, I find that optimal patent lives are sufficiently short to discourage imitation. With both patent length and breadth as instruments, the optimal policy consists of broad patents (no imitation allowed) with patent lives adjusted to achieve the desired reward. These results are in sharp contrast to recent results on the optimality of narrow, infinitely long patents.