The organization filed its first lawsuit against the Clintons shortly after its formation in 1994, and it pretty much never stopped. It is currently the plaintiff in more than 20 suits involving Mrs. Clinton, the Democratic presidential nominee.

“People always used to say to me, ‘What are you going to do when the Clintons leave?’” Tom Fitton, the president of Judicial Watch, said in an interview. “Well, the Clintons never really left.”

Neither has Judicial Watch, the indefatigable Clinton adversary that has probably done more than any other individual or organization to create the narrative that Mrs. Clinton is still battling: that she is untrustworthy.

It is a narrative that her Republican opponent, Donald J. Trump, has tried to exploit at every turn, whether he was labeling her “Crooked Hillary,” saying there was something “very fishy” about the suicide of her former law partner, Vincent W. Foster Jr., or suggesting that she might be concealing serious health problems.

Judicial Watch’s strategy is simple: Carpet-bomb the federal courts with Freedom of Information Act lawsuits. A vast majority are dismissed. But Judicial Watch caught a break last year, when revelations about Mrs. Clinton’s private email server prompted two judges to reopen two of the group’s cases connected to her tenure as secretary of state.

The lawsuits have since led to the release of hundreds of Mrs. Clinton’s emails — which have, in turn, spurred dozens of news releases and fund-raising letters from Judicial Watch that hype the significance of these documents, while putting them in the least flattering light possible for Mrs. Clinton.

The group’s lawyers were given permission to depose several of her senior aides from her time at the State Department. What is more, Mrs. Clinton herself will have to answer 25 detailed questions about her use of a private email server as secretary of state.

The questions, some with multiple parts, ask her to explain her rationale for using the private server and her reaction to warnings about the potential for security breaches, among other things. Her answers, to be provided via written testimony to the court, are due by Thursday.

Just getting this far has represented a victory for Judicial Watch, which operates out of a nondescript office building in the shadow of the Capitol.

Suing the government, repeatedly, is an expensive proposition; Judicial Watch has an annual budget of about $35 million that pays for close to 50 employees — a mix of lawyers, investigators and fund-raisers. Mr. Fitton says the group receives donations from nearly 400,000 individuals and institutions every year. One of its biggest funders, according to public filings, is the Sarah Scaife Foundation, which was created by the banking heir Richard Mellon Scaife, who died in 2014. In the 1990s, Mr. Scaife was one of the leading financiers of the right-wing effort to bring down the Clintons, bankrolling conservative think tanks and publications — as well as Judicial Watch.

Litigiousness is in the organization’s DNA: Its founder, Larry Klayman, once sued his mother. Mr. Klayman has described himself as a conservative Ralph Nader, but during Bill Clinton’s presidency, he often behaved more like a self-appointed Kenneth W. Starr, papering Washington with subpoenas related to every would-be Clinton scandal. His departure from the organization in 2003 was accompanied, unsurprisingly, by litigation: Mr. Klayman accused the organization, and his successor, Mr. Fitton, of “fraud, disparagement, defamation, false advertising and other egregious acts.”

Mr. Fitton responded that the allegations were “full of lies and distortions.” The suit is still in the courts.

Since he took over in 2003, Mr. Fitton has sought mainstream respectability for the organization.

It describes itself as a “nonpartisan educational foundation,” but Mr. Fitton says it is also a media organization. “We’re filling multiple roles here in a Washington where the traditional vehicles for government accountability have broken down,” he said.

Last year, he nominated Judicial Watch for three Pulitzer Prizes. He was told that because Judicial Watch was an advocacy group, it did not meet the Pulitzer committee’s eligibility criteria, a ruling he attributed to liberal bias.

If Mr. Fitton is seen as less flamboyant than his predecessor, he has been no less dogged in his pursuit of Mrs. Clinton. In 2009, Judicial Watch sued to prevent her from becoming secretary of state, claiming that an obscure clause in the Constitution prevented former members of Congress who voted to increase the salary of a government position from being appointed to that position.

For that matter, Judicial Watch is still suing the government to obtain a draft of the indictment against Mrs. Clinton that federal prosecutors prepared in 1998, when they were considering bringing charges against her in the Whitewater investigation.

“I think to say that they are not partisan would not be accurate,” said Representative Elijah E. Cummings of Maryland, the ranking Democrat on the House Committee on Oversight and Government Reform. “Look at the way that they have dealt with the Clintons. It seems as if they’ve been out to do them harm.”

According to Mr. Fitton, however, Judicial Watch’s persistence has been rewarded. “The documents we have uncovered in the last year or so are gobsmacking in terms of what they say about what Mrs. Clinton was up to, the depths of her criminality,” he said.

There is little doubt that the group has forced the release of government records that would otherwise have been kept from the public. More contentious is the claim that these documents illuminate Mrs. Clinton’s behavior, at least in the absence of the organization’s spin, which has broadly asserted that the Democratic presidential nominee used her position at the State Department to further the interests of her family’s foundation.

A Judicial Watch news release from August highlighted a newly disclosed 2009 email from a Clinton Foundation official to two of Mrs. Clinton’s senior aides at the State Department, requesting a meeting between a foundation donor and the United States ambassador to Lebanon. “Clinton’s top aides’ favors for and interactions with the Clinton Foundation seem in violation of the ethics agreements that Hillary Clinton agreed to in order to be appointed and confirmed as Secretary of State,” the organization wrote.

But the ambassador, Jeffrey D. Feltman, subsequently denied that the meeting had taken place.

Judicial Watch is a polarizing group, even among advocates for greater government transparency. Critics accuse it of weaponizing the Freedom of Information Act for political purposes. They argue that its unending barrage of lawsuits does more harm than good by draining federal resources, tying up the courts and wasting public servants’ time.

The Freedom of Information Act “is a legitimate tool for government transparency, but it’s possible to abuse it,” said Steven Aftergood, the director of the Project on Government Secrecy for the Federation of American Scientists. “There is a question about whether they are enriching or distorting political discourse.”

The group’s defenders argue that its success in bringing to light thousands of buried emails speaks for itself, and that people can ignore the organization’s spin and make their own decisions about what the records mean.

“They are obviously not just going on fishing expeditions, because they are producing documents that are resulting in stories and public debates,” said Danielle Brian, the director of the Project on Government Oversight.

Mr. Fitton, the Judicial Watch president, said his group fought just as hard for transparency during George W. Bush’s presidency. Notably, it teamed with the Sierra Club in an unsuccessful effort to obtain the records of Vice President Dick Cheney’s energy policy task force.

Judicial Watch’s claims of nonpartisanship will be tested if Republicans win the White House next month. For now, anyway, Mr. Trump seems safe from the group’s scrutiny. Mr. Fitton, when asked if he was concerned about the Republican nominee’s unwillingness to release his tax returns, said he was far more troubled by the Internal Revenue Service’s decision to audit Mr. Trump. “I think the I.R.S. is a Sword of Damocles over the First Amendment, and I think it is a menace,” he said.

And the pending federal action against Trump University for defrauding students? Mr. Fitton, whose organization has filed about 300 lawsuits against the Obama administration, described it as “ambulance chasing.”

As for Mrs. Clinton, she can expect to remain in the group’s sights whether she wins or loses. “Everyone wants to move on,” Mr. Fitton said. “We don’t move on.”

Continue reading the main story