Introduction: Why space law matters in war and peace

War and Peace in Outer Space examines the legal, policy, and ethical issues animating current concerns regarding the growing weaponization of outer space and the potential for a space-based conflict in the very near future. A collection of diverse voices rather than the product of a single scholarly mind, it builds upon a conference that was held in Philadelphia in April 2018, hosted by the Center for Ethics and the Rule of Law, at the University of Pennsylvania Law School, and designed by co-editor Cassandra Steer. The conference was an exceptionally high-level invitation-only roundtable for the duration of two days, attended by approximately thirty experts on space warfare from Canada, Europe, and the United States. In addition to calling attention to likely current and future threats to national and global security stemming from the use and misuse of the space environment, attendees suggested measures for ameliorating the risk of conflict in space, including international negotiation, transparency, and reporting on the use of space-based assets, and the establishment of clear rules, backed up by sanction regimes, against hostile actions that threaten the peaceful use of space by all nations.