After more than 30 years away from his alma mater, Cass R. Sunstein ’75—the most cited law professor in the U.S.—will be returning to Harvard to join the Law School faculty this fall.

“It feels like home. I love Cambridge,” Sunstein said from his office at the University of Chicago. “I’m excited, even thrilled.”

Sunstein, who graduated from the Law School, has published over 15 books and is highly regarded for his scholarship in fields including constitutional, administrative, and environmental law.

Law School Dean Elena Kagan has actively courted Sunstein and his longtime partner—renowned philosopher Martha Nussbaum—in recent years. Both have been visiting professors at Harvard in recent semesters, but Nussbaum has said that she will remain at Chicago, where Sunstein will also maintain an office.

Sunstein’s addition to the faculty fits a recent trend to bolster the school’s influence in constitutional and public interest law.

“For many years, Harvard Law School has had a reputation of being a place that has been hugely strong in corporate law, but wasn’t so strong in constitutional and public interest law,” said Richard H. Fallon, a constitutional law professor at the Law School. “I think this is an appointment that may shake up these reputations.”

In addition to Sunstein, the Law School has recently added several leading scholars in the field, including Noah R. Feldman ’92, formerly of New York University, and Michael J. Klarman of the University of Virginia.

When he returns to Harvard, Sunstein will also lead the Law School’s new Program on Risk Regulation.

Sunstein said that he hopes the program will be in a position to directly impact policies.

“It’s clear that the major policy issues facing the legal and political system all involve risks. The goal is to think about how to improve the legal system’s reactions to risk,” he said.

The areas the program will focus on include terrorism, natural disasters, and environmental law.

News that he had accepted an offer to join the faculty electrified the campus.

“This is just a fantastic development for Harvard Law School,” Fallon said. “In terms of making an appointment, we’ve landed a star of stars.”

In a statement released by Kagan yesterday, Kagan called Sunstein the “preeminent legal scholar of our time,” and voiced her excitement at his decision.

“This individual superstar is also the consummate team player, a person whose passion for reasoned intellectual inquiry is contagious and who raises the level of everyone around him,” Kagan said. “If I could add only one person to the faculty, Cass would be that person, and I am thrilled beyond measure to announce his appointment.”

Sunstein’s influence has also extended beyond the academic sphere. He has testified before the Senate during the Supreme Court confirmation hearings for Stephen G. Breyer and Robert H. Bork, as well as during the impeachment of former President Bill Clinton.

—Staff writer Kevin Zhou can be reached at kzhou@fas.harvard.edu.