Mr. O’Neil, who led U-Va. from 1985 to 1990, died Sept. 30 at 83. (UVA Law Library/University of Virginia)

Robert M. O’Neil, a scholar of First Amendment law who served in the 1980s as president of the University of Wisconsin System and then as president of the University of Virginia, where he was credited with recruiting more minorities to the faculty and student ranks, died Sunday at his home in Washington. He was 83.

The cause was congestive heart failure, said his son David O’Neil.

A Boston-born, Harvard-trained law professor, Mr. O’Neil arrived at U-Va. in 1985 as the university’s first president with “absolutely no ties to the South,” The Washington Post reported in a profile. He had previously led the 13-university system in Wisconsin for five years and was seen at his inauguration in Charlottesville as an outsider who would help raise the national profile of the institution founded by former president Thomas Jefferson as an “academical village.”

Mr. O’Neil remained in his U-Va. post until 1990, a notably short tenure at a university that had had only five previous presidents since 1905. Some colleagues described him as a “more of a professor than a president,” The Post reported when he stepped down, even as Mr. O’Neil was lauded for his financial stewardship of the university and his efforts to increase its diversity.

During Mr. O’Neil’s time as president, the U-Va. endowment increased to $470 million from $256 million, and outside research funding grew substantially, according to The Post. In addition to spearheading efforts to draw more minority students and faculty, he oversaw the establishment of a women’s center on campus and convened a task force that highlighted — and sought ways to remedy — the low number of female professors.

Mr. O’Neil at times encountered criticism for his leadership approach. To admirers, he was refreshingly deliberative; to critics, he was insufficiently decisive. Midway through his tenure, a provost was appointed to assist with administrative responsibilities.

A particular source of contention at the time was the question of whether and how much to expand the university. On one side were prospective students and parents who wished for greater enrollment opportunities; on the other were those who wished to maintain the campus’s relatively intimate feel.

“The president is bound to be caught between those competing forces,” A.E. Dick Howard, a law professor and longtime acquaintance of Mr. O’Neil’s, told The Post at the time. “How can he keep all the sides happy? . . . It calls for talents people associate with people negotiating the fate of the West Bank.”

After stepping down as U-Va. president, Mr. O’Neil spent two decades as founding director of the nonprofit Thomas Jefferson Center for the Protection of Free Expression. The organization, independent but tied to U-Va., seeks to defend First Amendment protections of religion, speech and the press through court briefs, public programming, and the awarding of so-called Jefferson Muzzle Awards for what it considers the flagrant violations of those freedoms. Mr. O’Neil retired in 2011.

Robert Marchant O’Neil was born in Boston on Oct. 16, 1934. His father worked in investment banking, and his mother volunteered for philanthropic causes.

At Harvard Mr. O’Neil received a bachelor’s degree in 1956 and a master’s degree in 1957, both in American history, and a law degree in 1961. Upon graduation he was a law clerk for Justice William J. Brennan Jr., who brought a sweeping liberal vision of the Constitution to the U.S. Supreme Court.

Mr. O’Neil taught at the University of California at Berkeley before beginning his career in academic administration. He served as provost of the University of Cincinnati and vice president of Indiana University at Bloomington before joining the University of Wisconsin in 1980. Throughout his career he continued teaching law even as he upheld his administrative responsibilities.

His books included “The Price of Dependency: Civil Liberties in the Welfare State” (1970), “Classrooms in the Crossfire” (1981), “Free Speech in the College Community” (1997) and “Academic Freedom in the Wired World” (2008).

Beyond his academic work, he served on the boards of organizations including the Commonwealth Fund, a private foundation that seeks to improve access to health care, and the financial services company then known as TIAA-CREF.

Survivors include his wife of 51 years, the former Karen Elson of Washington; four children, Elizabeth Layne of Austin, Peter O’Neil of San Francisco, David O’Neil of Chevy Chase, Md., and Benjamin O’Neil of Baltimore; and 13 grandchildren.

Mr. O’Neil’s interest in First Amendment law and his experience as a university administrator at times coincided. In 1992, he was asked to weigh in on the repeal of a ban at the University of Wisconsin on speech attacking one’s race, religion, sexual orientation, disability or heritage.

“The heyday of political correctness is over,” Mr. O’Neil, then at the Thomas Jefferson Center, told The Post. “Speech codes were unwise and for the most part unnecessary, even though they were adopted for the best reasons.”