The Clintons have been subject to fishing expeditions before, but why is a federal court making Hillary Clinton give sworn responses now to questions about her use of a private e-mail server back when she was secretary of state? This all stems from a Freedom of Information Act lawsuit brought by a conservative group seeking State Department information about Clinton’s aide Huma Abedin. With a series of permissive rulings, the judge has allowed the suit to get out of hand. It’s now an inquiry into Clinton’s motives in using her private server — something well beyond the contemplation of the freedom of information laws.

Judicial Watch, which initiated the suit, is a founding member of Hillary Clinton’s “vast right-wing conspiracy.” Founded by the lawyer Larry Klayman and given early funding by conservative billionaire Richard Mellon Scaife (remember him?), it brought some choice lawsuits against Bill Clinton back in the 1990s. Its favored method is the FOIA suit.

The latest iteration was filed in 2013 against the State Department, seeking information about the employment of Abedin, at one time Clinton’s deputy chief of staff at State and a magnet for Clinton conspiracy theorists.

The way a FOIA suit usually works is that a party seeks information, and the government undertakes to provide it. That’s it. Under the law, legal discovery — depositions and the like — is extremely rare. If the government shows the court that it has made a search reasonably calculated to retrieve all relevant documents, the case will be over at the summary judgement phase.

That’s how the current suit started — and for a moment, ended. After the State Department gave Judicial Watch the documents it was seeking, the two sides agreed to have the case dismissed in 2014.

Then things got strange. After the news media reported that Clinton had used a private e-mail server, Judicial Watch asked the D.C. district court to reopen the closed case to see if there were e-mails on the server that were relevant to the FOIA request.

The court agreed — and its decision was defensible. The State Department couldn’t have reviewed e-mails it didn’t have, so it made sense to extend the search. In response, the State Department reviewed the e-mails voluntarily provided by Clinton from her server, clintonemail.com, and passed them on.

That wasn’t enough for Judicial Watch, which then asked the court for more discovery “to uncover and present admissible evidence … about whether the State Department and Secretary Clinton deliberately thwarted FOIA,” and to learn about “the system itself to determine possible methods for recovering whatever responsive records may still exist.”

The court said yes again. Here’s where the case — and the court — began to go seriously off track. A FOIA suit seeks information from the government, not from its former officials. The State Department didn’t thwart the law, surely. And even if Clinton wanted to avoid disclosing documents, that’s not an issue for the court in this FOIA case. FOIA provides for no remedies for failure to comply, other than a court order to do so.

But the court didn’t see it that way. It said that there were questions about whether the State Department intentionally thwarted FOIA, and ordered discovery on that basis. As for possible remedies, it said that the law does not “impose limits” on the court’s equitable powers. That’s a nice way of saying the court thinks it can do whatever it wants to get the law enforced.

That still left the legal question of whether Clinton herself could be deposed. She argued that the public record, including her answers to the Federal Bureau of Investigation, already covers all relevant questions that Judicial Watch wants answered.

But the court held that Clinton hadn’t ever directly answered the question of why she used the personal server when it wasn’t compliant with State Department regulations or law. That’s true, as it happens — she hasn’t. There’s a probable reason for that. The Federal Records Act requires the government to keep records of important official communications. And although the law wasn’t officially interpreted to bar use of private e-mail accounts until 2015 — and has no criminal sanctions attached — Clinton wouldn’t want to say that she flouted it while secretary of state.

Clinton should no doubt answer the question directly, but nothing in FOIA and nothing in this case requires her to do so. The court is acting as a free-floating watchdog, which isn’t its job under FOIA.

The court also considered what’s called the “apex doctrine,” which stipulates that a high government official shouldn’t be made to testify unless there are exceptional circumstances, such as unique first-hand information that’s relevant. The court said Clinton qualified, because no one else knows why she used the private server. That’s only a plausible argument if you’ve already bought into the idea that she needs to answer the question why she did.

In an attempt at a compromise, the court said it wouldn’t order Clinton to be deposed in person, instead requiring her to answer written questions.

That’s got to be cold comfort for Clinton, who’s still being told to answer questions under oath while she runs for president.

The whole episode may seem like a minor instance of judicial overreach. And Clinton is partly responsible by virtue of her judgment in using the private server in the first place.

But history shows that fishing expeditions can potentially have serious consequences. Bill Clinton spent the years 1998 to 2000 dealing with wide-ranging depositions — while Osama bin Laden laid his plans.

By Noah Feldman

Noah Feldman is a Bloomberg View columnist. He is a professor of constitutional and international law at Harvard University. — Ed.