The Bill and Melinda Gates Foundation has announced the world’s strongest policy in support of open research and open data. If strictly enforced, it would prevent Gates-funded researchers from publishing in well-known journals such as Nature and Science.

On 20 November, the medical charity, based in Seattle, Washington, announced that from January 2015, researchers it funds must make open their resulting papers and underlying data sets immediately upon publication — and must make that research available for commercial reuse. “We believe that published research resulting from our funding should be promptly and broadly disseminated,” the foundation states. It says it will pay the necessary publication fees (which often amount to thousands of dollars per article).

The foundation is allowing two years’ grace: until 2017, researchers may apply a 12-month delay before their articles and data are made free. At first glance, this suggests that authors may still — for now — publish in journals that do not offer immediate open-access (OA) publishing, such as Science and Nature. These journals permit researchers to archive their peer-reviewed manuscripts elsewhere online, usually after a delay of 6–12 months after publication.

Allowing 1 year’s delay makes the charity’s OA policy similar to those of other medical funders, such as the UK Wellcome Trust or the US National Institutes of Health (NIH). But the charity’s intention to close off this option by 2017 might put pressure on paywalled journals to create an OA publishing route.

However, the Gates Foundation’s policy has a second, more onerous twist that appears to put it directly in conflict with many non-OA journals now, rather than in 2017. Once made open, papers must be published under a licence that legally allows unrestricted reuse — including for commercial purposes. This might include ‘mining’ the text with computer software to draw conclusions and mix it with other work, distributing translations of the text or selling republished versions. In the parlance of Creative Commons, a non-profit organization based in Mountain View, California, this is the CC-BY licence (where ‘BY’ indicates that credit must be given to the author of the original work).

This demand goes further than any other funding agency has dared. The Wellcome Trust, for example, demands a CC-BY licence when it is paying for a paper’s publication — but does not require it for the archived version of a manuscript published in a paywalled journal. Indeed, many researchers dislike the thought of allowing such liberal reuse of their work, surveys have suggested. But Gates Foundation spokeswoman Amy Enright says that “author-archived articles (even those made available after a 12-month delay) will need to be available after the 12-month period on terms and conditions equivalent to those in a CC-BY licence.”

Most non-OA publishers do not permit authors to apply a CC-BY licence to their archived, open, manuscripts. Nature, for example, states that openly archived manuscripts may not be reused for commercial purposes. So do the American Association for the Advancement of Science, Elsevier and Wiley and many other publishers (in relation to their non-OA journals).

“It’s a major change. It would be major if publishers that didn’t previously use CC-BY start to use it, even for the subset of authors funded by the Gates Foundation. It would be major if publishers that didn’t previously allow immediate or unembargoed OA start to allow it, again even for that subset of authors. And of course it would be major if some publishers refused to publish Gates-funded authors,” says Peter Suber, director of the Office for Scholarly Communication at Harvard University in Cambridge, Massachusetts.

“You could say that Gates-funded authors can’t publish in journals that refuse to use CC-BY. Or you could say that those journals can’t publish Gates-funded authors. It may look like a standoff but I think it’s the start of a negotiation,” Suber adds — noting that when the NIH’s policy was announced in 2008, many publishers did not want to accommodate all its terms, but now all do.

That said, the Gates Foundation does not leave as large a footprint in the research literature as the NIH. It funded only 2,802 research articles in 2012 and 2013, Enright notes; 30% of these were published in OA journals. (Much of the charity’s funding goes to development projects, rather than to research which will be published in journals.)

The Gates Foundation also is not clear on how it will enforce its mandate; many researchers are still resistant to the idea of open data, for instance. (And most OA mandates are not in fact strictly enforced; only recently have the NIH and the Wellcome Trust begun to crack down.) But Enright says that the charity will be tracking what happens and will write to non-compliant researchers if need be. “We believe that the foundation’s Open Access Policy is in alignment with current practice and trends in research funded in the public interest. Hence, we expect that the policy will be readily understood, adopted and complied with by the researchers we fund,” she says.