A federal judge cleared the way Wednesday for lawyers from a right-wing watch-dog group to take sworn testimony from top Hillary Clinton aides and opened the door for the group to seek an interview with Clinton herself later. But while the ruling is another political blow for the Clinton campaign, legally the former Secretary of State can thank one of her predecessors, Henry Kissinger, and former Supreme Court Chief Justice William Rehnquist, for providing her with a robust defense in a similar case more than 35 years ago.

The depositions of Clinton’s aides are to take place over the next eight weeks as part of a long-running Freedom of Information Act (FOIA) suit brought by the group, Judicial Watch. In November 2013, the group sued the State Department in an effort to obtain information about the simultaneous employment of Clinton’s close aide, Huma Abedin, by the State Department, Bill Clinton’s charitable Foundation and a for-profit consultancy, Teneo, which built a successful business around its access to the former president.

In response to the suit, State produced eight documents to Judicial Watch, and the FOIA case was closed the following March. But a year later, the New York Times reported the existence of Hillary Clinton’s private server and last June the case was reopened—an extraordinarily rare occurrence in FOIA law—and several dozen other e-mails were produced. In seeking to depose Clinton’s aides, Judicial Watch alleged that State still hasn’t adequately complied with FOIA and that the Democratic front-runner, her aides and the State Department had intentionally tried to thwart the law by setting up the server. “Mrs. Clinton didn’t want anyone looking at her e-mails,” says Tom Fitton, Judicial Watch’s president.

In his order Wednesday, Judge Emmet Sullivan of the federal district court in Washington, D.C., gave credence to that allegation. Taking sworn testimony in a FOIA case is rare, but Sullivan approved a discovery plan presented in March by Judicial Watch to interview Abedin and another top Clinton aide, Cheryl Mills, as well as five current and former State Department officials. The group is limited to asking questions about why Clinton set up and used a private server for all her work and personal emails as Secretary of State and how the State Department responded to the group’s FOIA request.

Sullivan has said it is an open question whether Clinton’s private email system was set up deliberately to thwart FOIA. In February, Sullivan noted the State Department’s Inspector General had recently reported that Mills was aware of both the FOIA request from Judicial Watch and the private e-mail server. He also pointed out that at least one State Department official has said that documents on the private server should have been provided in another FOIA case, but weren’t. And he has repeatedly referred to an email exchange from early in Clinton’s tenure at State, where Abedin rejected a proposal to run a private e-mail system out of State after a top official told her it would be subject to FOIA.

Clinton herself has repeatedly said the private server was set up as a matter of convenience. But in open court last February, Sullivan said “We’re talking about a Cabinet-level official who was accommodated by the government for reasons unknown to the public.” Sullivan suggested State knowingly failed to comply with FOIA as part of that accommodation. “I’m hard-pressed to find that the government didn’t know [about the server], so one of the big questions is: Why did it take until 2015” for State to do an adequate search?

As bad as the ongoing case may seem for Clinton politically, legally she has less to worry about. The case is not criminal, but civil, which means the only likely consequence of a Judicial Watch victory would be Clinton or her aides having to turn over more documents for review and possible release by State. Those documents could include any e-mails Clinton’s associates deleted as “personal,” if they exist: some may have been recovered by the FBI as part of its separate criminal investigation into how classified information got onto the private server.

Here’s where Clinton’s predecessor comes in. Kissinger, who served as Secretary of State under presidents Nixon and Ford, has already done much of the work ensuring she won’t pay a price for her unorthodox use of a private server. As Secretary of State, Kissinger kept transcripts of some of his work calls. In the pre-electronic era, he took the only copies with him when he left government in the mid-1970s, storing them at Nelson Rockefeller’s estate in Westchester and then transferring them to the Library of Congress with tight restrictions on who could look at them.

The Reporters Committee for Freedom of the Press sued for access, but then-Justice William Rehnquist, a Nixon appointee, ruled in a 5-2 decision that State had no obligation to search for documents that had been removed from the department, even if they had been improperly taken, because they were no longer in their possession. Judicial Watch is hanging its hopes on a footnote in which Rehnquist writes that his ruling might not apply in a case where someone is actively trying to thwart FOIA.

In his dissent to Rehnquist’s ruling, Justice John Paul Stevens said it would be “unseemly to invite litigation and discovery into the subjective motivation of agency officials responsible for processing the flood of paper that threatens to engulf today’s bureaucracy.” Judge Sullivan, who was appointed by Bill Clinton to the federal court, clearly disagrees. In any case, the Kissinger case may not be enough to protect Clinton from further political fallout. In court last February, Sullivan threatened to issue a subpoena for any outstanding records of Clinton’s emails, work-related or otherwise. And if the depositions of Abedin, Mills and the State Department officials convince Sullivan that there was an attempt to thwart FOIA, he could order Clinton herself to be deposed just as the general campaign heats up in the fall.