How does antitrust enforcement against patent-based monopolies affect innovation? I address this question by empirically studying the US antitrust case against Xerox, the monopolist in the market for plain-paper copiers. In 1975, Xerox was ordered to license all its copier-technology patents in...

We study the 1956 consent decree against the Bell System to investigate whether patents held by a dominant firm are harmful for innovation and if so, whether compulsory licensing can provide an effective remedy. The consent decree settled an antitrust lawsuit that charged Bell with having...