This article reflects the views of the authors and not necessarily those of their institutions of employment or affiliation. This article was first written as a “white paper” for the Group on Earth Observations (GEO) under Task DA-06-01, “Furthering the Practical Application of the Agreed GEOSS Data Sharing Principles,” which was led beginning in 2006 by the Committee on Data for Science and Technology (CODATA) of the International Council for Science (ISCU) under the auspices of the GEO Architecture and Data Committee. We would like to thank the many individuals who helped facilitate the writing of the article or its review. These include Michael Rast, Michael Tanner, and Masami Onoda of the GEO Secretariat, and Kathleen Cass of the CODATA Secretariat, all of whom provided a great deal of project guidance and administrative support; Charles Barton, Australian National University, and Jack Hill, the U.S. Geological Survey, for their contributions to the drafting of the article; Santiago Borrero, Dora Ann Lange Canhos, Yukiko Fukasaku, Huadong Guo, Alexei Gvishiani, Bernard Minster, Steve Rossouw, and Fraser Taylor for providing review comments on earlier drafts; and the many representatives to GEO from its Member States or Affiliated Organizations, who also provided significant substantive comments and suggestions. We also acknowledge the strong support and encouragement of José Achache, Director of the GEO Secretariat, who recognized early on the importance of this effort. Finally, we wish to thank the editors of the Journal of Space Law and the CODATA Data Science Journal, for their assistance with the publishing of this article.