Stanley Kutler, shown here in 2013, died April 7 at 80. (Michelle Stocker/Capital Times via Associated Press)

Stanley I. Kutler, a noted Watergate scholar who became part of the history he studied by filing a lawsuit that spurred the release, beginning in the 1990s, of hundreds of hours of President Richard M. Nixon’s secretly recorded conversations, died April 7 at a hospice in Fitchburg, Wis. He was 80.

The cause was congestive heart failure, said his son David Kutler.

Dr. Kutler was a longtime professor at the University of Wisconsin at Madison and began teaching history more than a decade before Richard M. Nixon became, in 1974, the first U.S. president to resign his office.

Dr. Kutler would later dedicate himself to the task, also pursued by journalists and other academics, of fully illuminating the events collectively called the Watergate scandal. His book “The Wars of Watergate” (1990) was described by journalist and author J. Anthony Lukas as “the first major work by a professional historian to focus on the scandal and the investigations that felled the Nixon Presidency.”

In Nixon, presidential historians encountered a subject who had documented his time in office more extensively than any other occupant of the White House. From February 1971 to July 1973, Nixon secretly taped his conversations and phone calls at locations including the Oval Office and the nearby Old Executive Office Building.

Previous presidents had recorded their conversations, but Nixon was the first to employ a voice-activated system instead of one that was manually turned on and off. In all, the recording system captured 3,432 hours of conversation between Nixon, his aides and visitors, according to Ken Hughes, a historian at the University of Virginia’s Miller Center who has written two books about the contents of the tapes.

Approximately 60 hours of conversation were used during the Watergate inquiries of the 1970s. The remaining tapes were preserved by an act of Congress, but after leaving office, Nixon began an effort to prevent their public release.

He and his defenders argued that the tapes included private information and that, with their release, Nixon would have been subjected to excessive scrutiny.

In 1992, Dr. Kutler and Public Citizen, the public-interest group founded by consumer-rights advocate Ralph Nader, filed a lawsuit seeking the release of the remaining tapes.“I’m a historian,” Dr. Kutler told the Boston Globe. “I thought it was important to liberate these documents.”

In 1996, two years after Nixon’s death, a settlement was reached with his estate and the National Archives. Later that year, the first set of tapes — 201 hours related to the events classified as abuses of power — was released to the public. Dr. Kutler hired court reporters to conduct the arduous task of transcribing the poorly made recordings for his book “Abuse of Power: The New Nixon Tapes” (1997).

“We’re up against an enemy, a conspiracy,” Nixon, as quoted in Dr. Kutler’s book, told aides H.R. Haldeman and Henry Kissinger shortly after the publication of the Pentagon Papers. “They’re using any means. We are going to use any means. Is that clear?”

Reviewing Dr. Kutler’s book in The Washington Post, political scholar Matthew Dallek wrote that the tapes “reveal in more detail than ever ‘what the president knew and when he knew it,’ make clear that this was a White House awash in corruption, and serve as a timely reminder that there is a difference between personal peccadilloes and political corruption. It’s hard to imagine a more explosive set of documents.”

Defenders of Nixon faulted Dr. Kutler for the elisions he made in order to fit the sprawling conversations into a 700-page book. “What additional exculpatory material lies on the editor’s floor?” John H. Taylor, Nixon’s post-White House chief of staff, wrote in the American Spectator, describing Dr. Kutler as “dean-for-life of the Nixon-haters.”

“If there were anything exculpatory in these tapes,” Dr. Kutler replied, “Nixon would have let it out a long time ago.”

To date, 2,658 hours of the Nixon tapes, covering a swath of topics in domestic and foreign policy, have been released, according to Hughes.

“I am quite convinced that had it not been for Stanley Kutler’s efforts in the 1990s, the Nixon tapes would have stayed unreviewed a lot longer,” Timothy Naftali, the first federal director of Nixon’s presidential library, said in an interview. “It is rare that a single, determined scholar can move a government to reveal materials that don’t put it in a good light,” Naftali continued. “It’s rare, and it’s a wonderful thing in a democracy.”

Stanley Ira Kutler was born in Cleveland on Aug. 10, 1934. He received a bachelor’s degree in political science from Bowling Green State University in Ohio in 1956 and a PhD in history from Ohio State University in 1960.

Dr. Kutler taught at universities in Ohio, Pennsylvania and California before joining the University of Wisconsin, where he retired in 1996. In addition to his volumes on the Nixon administration, he wrote a play, “I, Nixon,” and wrote or edited numerous volumes on the American judiciary and 20th-century U.S. history.

His son Jeff Kutler died in 2010. Survivors include his wife of 58 years, Sandra Sachs Kutler of Madison, Wis.; three children, David Kutler of Minneapolis, Andrew Kutler of Arlington, Va., and Susan Kutler Saltzman of Hinsdale, Ill.; and seven grandchildren.

Dr. Kutler described his work on the Nixon tapes as “a long painful process, not unlike mining a mountain of paper to get a few nuggets.”

“But this was a whole new experience in dealing with the history of a president,” he told the New York Times in 1997. “Here were spontaneous, off-the-cuff presidential remarks, day after day. The spoken word from the man himself is an extraordinary thing. I’ve had a rare experience as an historian, to be the midwife to the creation of a document. . . . Documents are usually musty and crusty. I like to think I gave it some life.”