Dr. Rosenthal, of Princeton, was respected for his academic credentials, but just as much for his practical knowledge of New Jersey and the legislative process.
"He had a well-earned reputation of being a straight-up, calls-them-as-he-sees-them kind of guy," said Assemblyman John Wisniewski (D., Middlesex), who led the Democrats on the commission.
"It was very hard to imagine there being anybody other than Alan Rosenthal for that job."
The former director of the Eagleton Institute of Politics at Rutgers and a member of the faculty until his death, Dr. Rosenthal made a career out of an uncommon calling: studying state legislatures.
"He was one of the few people I met who liked legislatures," said former Republican Gov. Thomas H. Kean, who met Dr. Rosenthal while serving in the Assembly in the 1960s. "He did everything he could to improve their lot."
Credited by colleagues with elevating the state legislature to the stature of the two other branches of government, Dr. Rosenthal advocated for professional legislative staffs and budgets to pay for policy research. The model he championed was duplicated across the country, said Ben Dworkin, director of the Rebovich Institute for New Jersey Politics at Rider University.
"The modern professional legislature in New Jersey, definitely, and pretty much throughout the country, is a product of Alan Rosenthal's analyses and critiques," Dworkin said.
A graduate of Harvard College who earned a master's degree in public administration and a doctorate from Princeton University, Dr. Rosenthal began his career when "very few people, very few scholars, had even noticed legislatures," said Ruth Mandel, director of the Eagleton Institute.
He had a passion for the legislative process, but he also "loved the people there," Mandel said. "He was not a scholar sitting at a distance with a notebook and a kind of scholarly shield in front of him. He just got in there."
At Eagleton, Dr. Rosenthal brought in lawmakers and staff to talk to students. He served as a mentor, influencing many careers, former students said.
"He was a guy who said: 'This should be popular. These people do good work,' " said Dworkin, who studied under Dr. Rosenthal. "I think that attitude rubbed off on those who were trying to consider political life."
Dr. Rosenthal held conferences for lawmakers from across the country. He consulted legislatures in 35 states. In New Jersey, he served on congressional redistricting commissions in 1992 and 2001, followed by the commission in 2011.
He was chosen because of "his demonstrated expertise," said U.S. Rep. Leonard Lance (R., N.J.), the minority leader of the state Senate from 2002 to 2008, who previously served in the Assembly.
"It's rare when you have a distinguished academic who also knows the nuts and bolts of the legislative process. And he knew both," Lance said.
As the Democrats and Republicans presented new versions of proposed maps, Dr. Rosenthal "was very sphinxlike," Wisniewski said.
Both sides struggled to read him, analyzing his behavior during coffee breaks at the conference center in New Brunswick. On the final day, Wisniewski said, Dr. Rosenthal walked into the room where the Democrats were and ended the drama with little fanfare.
"He simply said, 'I'm going to go with your map,' " Wisniewski said.
Dr. Rosenthal is survived by his wife, Lynda Kresge; two sons; two daughters; two stepsons; and eight grandchildren. His family is holding a private service. The Eagleton Institute will celebrate his career in September.
Elected officials across the state issued condolences Thursday, including Gov. Christie.
"Alan was a true New Jerseyan," Christie said in a statement. He said New Jersey "has lost a great advocate and, on behalf of the people of our state, I offer condolences to the Rosenthal family."
Democratic gubernatorial candidate State Sen. Barbara Buono (D., Middlesex) said in a statement that Dr. Rosenthal was "a brilliant man, deeply passionate about New Jersey and perfecting its political systems."
As rare as Dr. Rosenthal's love for legislatures was his respect by members of both political parties, said Bill Castner, a lawyer who served as chief counsel to Gov. Jon S. Corzine.
"Democrats and Republicans - do they agree on anything?" said Castner, a former student of Dr. Rosenthal's who served as counsel to the Democrats on the 2011 redistricting commission. He said Dr. Rosenthal was "a professional in every sense of the word."
Contact Maddie Hanna at 856-779-3232 or email@example.com, or follow on Twitter @maddiehanna