Paul G. Mahoney, a former dean of the law school at the University of Virginia, was named the institution’s interim president on Monday, after his predecessor as president resigned under intense pressure from the Trump administration.

The university’s governing board met on Monday to approve Mr. Mahoney’s appointment. He is taking over the helm of a university that was operating in a leadership vacuum as it attempted to negotiate a tricky legal predicament posed by several Department of Justice investigations.

The former president, James E. Ryan, left in July following a campaign waged against him by the Department of Justice and a conservative Virginia alumni group, the Jefferson Council, that led a multiyear crusade attacking the school’s diversity, equity and inclusion programs. The university’s longtime provost and second-highest executive, Ian Baucom, left earlier in the year to become president of Middlebury College.

Members of the university’s board, who are appointees of Gov. Glenn Youngkin, a Republican, said at the meeting Monday that they hoped to select a new permanent president within four to six months.

Reached on Monday after the announcement, Mr. Mahoney said he knew he had been nominated for the interim presidency by several former students, colleagues and alumni, but that he was otherwise “coming in cold,” and had not been briefed on the details of the Trump administration’s actions against the university.

“I think my first goal is going to be to reach out to as many constituencies as possible to get their perspectives and concerns and ideas,” he said.

Mr. Mahoney, 66, served as dean of the law school from 2008 to 2016, and continues to teach there. Regarded as a pragmatic administrator who led the law school successfully through the national financial crisis, Mr. Mahoney is a libertarian-leaning legal thinker who has argued in his writing that securities regulation has been ineffective.

His other areas of expertise include law and economic development, corporate finance, financial derivatives and contracts. His wife, Julia D. Mahoney, is also a professor at the law school.

A member of the Council on Foreign Relations, Mr. Mahoney joined the law school faculty in 1990 after practicing law with the New York firm of Sullivan & Cromwell. He clerked for both Supreme Court Justice Thurgood Marshall, a staunch liberal, and for Judge Ralph K. Winter, Jr., an appellate judge who was regarded as a leading conservative.

Mr. Mahoney holds degrees from the Massachusetts Institute of Technology and Yale Law School.