CHAMPAIGN — Friends and colleagues of Larry Ribstein say they'll remember him as a first-rate legal scholar and original thinker who enjoyed debate and was an expert in business law.

They also recall him as a generous person who was a gifted photographer and an authority on movies and the law.

Mr. Ribstein, 65, a professor in the University of Illinois College of Law since 2002, died Saturday in Fairfax, Va.

Henry Butler, a law professor at George Mason University who co-wrote several books and articles with Mr. Ribstein, said the UI professor started feeling bad while taking a walk Thursday with his wife.

"Thirty-six hours later, he's gone," Butler said.

Mr. Ribstein's death "came as a shock," said Bruce Smith, dean of the UI College of Law.

"Larry was a scholar of incandescent intellect, breathtaking range and unflagging energy," Smith said.

Mr. Ribstein specialized in corporate and securities law and topics such as financial regulation and white-collar crime.

"His interests were very expansive," Smith said. "He was very prominent in the world of blogging, and his ideas were shared across the nation and world."

Ribstein was a leading contributor to the "Truth on the Market" blog. He was also the college's associate dean for research and co-director of the Illinois Business Law and Policy Program.

"I remember his fierce intensity about everything he did," said Andrew Morriss, a former colleague at Illinois who is now a law professor at the University of Alabama. "He turned it up to 11 on everything."

"He was one of the few original thinkers in law," Morriss said. "Most legal scholarship is recycling, but Larry had original thoughts."

Smith said Mr. Ribstein had "an incredible passion for ideas" and was "a person of wide-ranging interests and incredible engagement,"

He called Mr. Ribstein "the world's leading scholar" on unincorporated businesses, such as partnerships.

"No scholar in the world wrote as compellingly or influentially on the 'uncorporation' as he did," Smith said, referring to Mr. Ribstein's book, "The Rise of The Uncorporation," published in 2010.

Mr. Ribstein was also influential in the field of jurisdictional competition and wrote extensively about legal education and the legal profession, Smith said.

UI law Professor Nuno Garoupa said Mr. Ribstein's "recent work on the death of the big law firm and the need for a complete transformation of legal education attracted a lot of attention."

Garoupa called Mr. Rib- stein "a true intellectual, a man who loved ideas and enjoyed the exchange of viewpoints in an open but serious and rigorous discussion.

"He was not the easygoing scholar who is afraid of taking sides or challenging the established dogmas in legal academia," Garoupa said in an email.

Mr. Ribstein "always wanted everything to be the best," Morriss said. "He didn't tolerate the second-rate. He drove everyone else hard, and he drove himself hard. You wanted to live up to his expectations. ... You don't get to be around an intellect like that very often."

In discussing ideas, Mr. Ribstein didn't sugar-coat things, Morriss said.

"It's never comfortable to be told you're an idiot, but he didn't have a malicious bone in his body," Morriss said. "He was a kind and generous person who threw everything into all he did."

One of Mr. Ribstein's favorite fields was law and the movies, Garoupa said.

"He was a true expert on the subject with encyclopedic knowledge about the movie industry," Garoupa said.

Mr. Ribstein was also a fine photographer, shooting both landscapes and urban scenes, Morriss said.

Smith said Mr. Ribstein was a mentor to many people within the law field.

"He invested selflessly in the professional development of junior faculty members — whether at Illinois or at other institutions," Smith said.

Butler praised Mr. Ribstein's "creativity and perseverance" in developing ideas and theories.

"He was very thorough, very creative and on the cutting edge of a lot of debates in corporate law and securities law," Butler said.

Debate in general was appealing to Mr. Ribstein, he added.

"If there wasn't one to be had, he would come up with one," Butler said.