Public business is public business, regardless of where a public servant conducts it. That’s the essential conclusion of the U.S. Court of Appeals for the District of Columbia Circuit, which issued a decision this week reversing a lower court’s ruling. The opinion held that a federal agency cannot shield records from search or disclosure under the Freedom of Information Act (FOIA) by storing them in a private email account controlled by the agency head.

The case in question focused on a FOIA brought by the Competitive Enterprise Institute for work-related correspondence of John Holdren, the director of the White House Office of Science and Technology Policy, that was conducted on a non-official account at the Woods Hole Research Center. OSTP refused to provide records for the FOIA, arguing that the emails were “beyond the reach of the FOIA” because they were in an account “under the control of a private organization.”

Sunlight expects this court decision to have an impact on existing and future FOIA lawsuits and federal public records requests, given the clear guidance on private email being subject to public records requests, but it’s not clear yet how much it will affect former Secretary of State Hillary Clinton, who is undoubtedly now the most high-profile user of a personal email system during her tenure in office.

As Josh Gerstein reported for Politico, the court’s decision is likely to bolster the legal cases of groups seeking more answers about her use of a personal email server.

The Federal Bureau of Investigation will now be the target of both congressional subpoenas about the case and FOIA requests — and likely subsequent lawsuits — for the thousands of other emails Director James Comey said forensic investigators discovered and reconstituted.

Those messages and their contents will matter to public knowledge about the recent history of the United States, in terms of continuing reporting and disclosure of what the former secretary of state wrote about various matters of public interest during 2009-2012, from trade to Iraq, Libya or other foreign policy decisions.”

The fact that these emails were kept on an unofficial system has now become much harder to invoke as a justification for nondisclosure, or as an excuse not to search through them. The court’s decision means that there is one less potential justification for denying access to the emails that were requested under FOIA, as litigation continues. It also heightens the sense in which the personal email arrangement resulted in an explicit thwarting of the FOIA process and explicitly undermined public access to public records.

More broadly, in a historic moment when the temptation and incentives for public servants to use personal devices and email to keep correspondence outside of the reach of public records laws continues to endure, this decision is a critical addition to our national discourse. The use of shadow systems outside of the knowledge of agency FOIA officers pose genuine challenges to the accountability and transparency the public expects of its government. This court decision makes it clear that if a non-government messaging system is used by a public official, a FOIA request extends to any records created on it.

We hope that our elected officials and government workers keep the people’s business on government systems and devices. When they do not, we expect the courts to uphold the people’s right to access information outside of them.