John Hart Ely, an innovative legal theorist and former Harvard professor whose ideas about constitutional interpretation widely influenced the discourse on democracy and the law over the past quarter century, died of cancer on Oct. 25 at his home in Coconut Grove, Fla. He was 64.

During his tenure at Harvard Law School (HLS), Ely served as the school’s first chair in constitutional law and wrote his most influential book, Democracy and Distrust: A Theory of Judicial Review.

In the book, Ely (pronounced EE-lee) argued that judges cannot interpret the Constitution by its language and history alone, nor can they infer a code of morality from it. Instead, Ely said, judges have an obligation to protect the democratic process as laid out in the Constitution.

Since 1978, Democracy and Distrust has been cited more times than any other legal work, according to a study published in the January 2000 edition of The Journal of Legal Studies.

The same study named Ely as the fourth most frequently cited American legal scholar of all time, trailing only Richard A. Posner, Ronald Dworkin and Oliver Wendell Holmes Jr., Class of 1829.

Ely also explored issues of free speech, racial discrimination and voting rights in the book.

A professor at the University of Miami School of Law since 1996, Ely also taught at Yale and served as dean of Stanford Law School from 1982 to 1987.

Tyler Professor of Constitutional Law Laurence H. Tribe ’62—who succeeded Ely as HLS’s expert in the field—said he would miss Ely, whom he considered a close friend.

“Ely’s tendency to keep to himself and to avoid the flamboyant public gesture might have prevented him from cutting as dashing a swath through this community as some of my more colorful colleagues manage to do,” Tribe wrote in an e-mail. “But for those of us who were lucky enough to be among this very private man’s real friends, his death leaves an enormous rip in the human tapestry.”

Tribe said that Democracy and Distrust was “the most important contribution” to the subject of judicial review in the last 25 years.

Ely’s other books include War and Responsibility: Constitutional Lessons of Vietnam and Its Aftermath and On Constitutional Ground.

Born in New York City in 1938, Ely spent his undergraduate years at Princeton University.

During the summer after his second year of law school at Yale, Ely worked as a summer clerk at the Washington law firm Arnold, Fortas & Porter.

He assisted future Supreme Court Justice Abe Fortas in 1962 with the preparation of a brief on behalf of Clarence E. Gideon, a destitute Florida man who was tried and convicted without legal representation.

The next year, the Supreme Court ruled in Gideon v. Wainwright that the government must provide attorneys to those who cannot afford them.