Novelty value is one of the legal requirements for a patentable innovation but it has been given relatively little attention in the literature. It is often abstracted away by assuming that any innovation is patentable. We study the optimal novelty requirement in a model where ideas are scarce,...

We argue that a patent system makes collusion among innovators more difficult. Our simple argument is based on two properties of the patent system. First, a patent not only protects against infringement but also against retaliation by former collusion members. Second, a deviator has an equal...