James Watt's 1769 patent is widely supposed to have stood in the way of the development of high-pressure steam technology until it finally expired in 1800. We dispute this popular claim. We show that, although it is true that high-pressure steam technology developed only after the expiration of...

In a patent infringement suit, the alleged infringer wins with a ruling of either patent invalidity or non-infringement. It is ambiguous which of these outcomes is preferred by the alleged infringer. Invalidity may increase current-period competition, but simultaneously removes constraints to...

We identify welfare-optimal patent royalties in a model of costly imitation, entry and imperfect competition. When the social planner may impose a compulsory license, optimal royalties either blockade imitation, facilitating unregulated monopoly, or yield an aggregate-zero-profit "efficient"...