“Open Data” is a principle that some kinds of scientific and scholarly data should be freely available to anyone to use and republish as they wish, without restrictions from copyright or other limits. Open Data is distinct, but related in spirit, to the Open Access to scholarly publications movement.
The argument for Open Data often focuses on the source of funding for research, stating that when public/governmental funding is used to support research, that research is properly owned by the public at large and should be made publicly available. Consistent with the Open Data notion, U.S. Federal law has long upheld that raw facts are not copyrightable (though the means of expression -- styled papers, tables, charts, and other containers presenting the data -- are).
Open Data is a de facto standard for data in some scientific fields, notably molecular biology. Molecular biologists wishing to publish articles on newly sequenced DNA or other biomolecules have long been required to deposit those sequences in archival databases at the National Center for Biotechnology Information. This allows other researchers, once the publication and data is released, to view the new sequences and make use of them in their own work; the broad availability of this data has been widely recognized as being critical in advances in modern biology.
Recently the National Science Foundation implemented a policy requiring grant applicants to incorporate a data management plan into their grant proposals. While the NSF policy does not endorse or require Open Data per se, it is hoped the requirement will encourage researchers to carefully consider the long-term accessibility of their research products, which is the fundamental concern of the Open Data movement. The University Libraries Scholarly Commons is available as an open archive for research materials produced by Miami researchers.