This chapter details how competition laws have, to date, addressed matters associated with interoperability standards and SEIP. Particular focus is given the essential facilities doctrine. In the United States, the essential facilities doctrine has been abandoned; in the EU, refusal to licence can constitute an abuse of a dominant market position in the relatively narrow circumstances outlined in the ‘exceptional circumstances’ test applied in the Magill and IMS Health cases. Consideration is also given to the law and economics analysis of the relevant laws and practices. It is concluded that the essential facilities doctrine, as applied to interoperability standards and SEIP, would not provide a helpful basis for binding disciplines at the international level because of entrenched differences between leading jurisdictions, as well as its questionable standing in the context of law and economics scholarship. The work also includes discussion and analysis of other applicable principles of competition law in the context of interoperability standards, including concerted practices, fraud or misconduct in the creation of standards, tying, and the somewhat controversial doctrine of excessive pricing.