From the Smithsonian’s Unbound Blog:
The Smithsonian will soon develop procedures for complying with the White House Office of Science and Technology Policy’s directive on public access to federally funded research.
That means that most papers authored by Smithsonian staff and affiliates will be made available to the public at no charge, some after an embargo period. There are several methods being developed by other federal agencies to meet this requirement and the Smithsonian has kept abreast of these policies. [Our emphasis] But aside from the White House mandate, it is clear that Smithsonian authors are increasingly making their scholarship freely available via publishing with an open access (OA) publisher. On average, there are about 350 OA papers published each year by Smithsonian scientists. This represents nearly 15% of research output.