This past summer, a relatively obscure 23-year-old organization known loosely as the Federalist Society entered the news cycle because it emerged that Judge John G. Roberts Jr., nominated for a spot on the Supreme Court by President Bush, had once been a member of the conservative group. Or not. The confusion was never fully cleared up: although the White House denied that Roberts had belonged to the organization, The Washington Post reported that the judge had served on one of the organization’s steering committees. But it became clear that the 35,000-member Federalist Society reached into the highest echelons of U.S. government.

It turns out that one of the group’s cofounders, Steve Calabresi, teaches law at Northwestern University. Calabresi doesn’t dispute the organization’s reach, but he does downplay its influence. “The society doesn’t take positions on policy,” he says. “We don’t advocate; we don’t lobby; we don’t litigate. It is true that many of our members are active in politics and have done remarkable things, but not pursuant to Federalist Society policy.”

Spend just a few minutes talking with Steve Calabresi and you will understand a critical element in the conservative juggernaut that has swept across America’s political landscape over the past 25 years: a sense of fun. Calabresi, 47, exudes an infectious exuberance and delight, whether discussing his stint at the Reagan White House, his 15 years instructing would-be lawyers on the intricacies of constitutional doctrine, or his political transformation during college that led to his helping found the Federalist Society for Law and Public Policy Studies.

So exactly what does the group do? “We enjoy lively debate and discussion,” says Calabresi. Certainly those dialogues have included some of the most prominent conservative speakers of the day: Judge Robert Bork and future Supreme Court justice Antonin Scalia addressed the organization’s first national conference. But, adds Calabresi, “we tried from early on to also have the best liberal speakers around. I thrived on that kind of give-and-take-the kind of thing universities should foster, but all too often don’t.”

Born in Madison, Wisconsin, in 1958, he grew up in Connecticut and Rhode Island. Calabresi says his father, a scientist specializing in cancer research, helped him “realize the importance of understanding what works in the real world,” while his uncle Guido Calabresi, a former Yale Law School dean and current federal appeals court judge, was equally influential. “He got me interested in the law, and his example inspired me toward a career in teaching the law,” says Calabresi, who describes his uncle as a Clinton Democrat. “He was a role model and a mentor, though our politics came out on different sides.”

The young Calabresi arrived at Yale College in 1975 still a centrist Democrat (he voted for Jimmy Carter in 1976), but swayed by new friends, the failures of the Carter administration, and his studies in economics, he began his gradual shift to the right. Despite opposition from the Yale Daily News, he helped organize debates through the Yale Political Union between people with widely diverging views-the most notorious being the 1978 encounter between former U.S. congressman Allard Lowenstein and a representative of the Palestine Liberation Organization.

Taking a break between college and law school, Calabresi spent part of his time campaigning for Ronald Reagan in 1980. “It was probably at this point that my transformation completely took hold,” he says. He arrived at Yale Law School only to learn of the imminent departure of the two conservative professors-Bork and Ralph Winter, both headed for judgeships-he had most wanted to spend time with.

“I figured if we were going to have any interesting libertarian or conservative [speakers], we would have to import them.”

And so was born the Federalist Society, with chapters opening simultaneously at the law schools at Yale and the University of Chicago; Scalia taught at the latter and advised the group there. In addition to its A-list of conservative speakers, the group’s first conference, held at Yale in April 1982, attracted about 150 people, some of them students from other campuses who would start chapters of their own. “The conference was very entertaining,” says Calabresi, almost giddy. “None of us had ever been in a situation with that many conservatives around. It was a lot of fun.”

Following law school, Calabresi began putting together an impressive résumé. He clerked for Winter and Bork; served as a special assistant to U.S. attorney general and Reagan intimate Edwin Meese (“a very heady and exciting time”); and clerked for Supreme Court justice Scalia (“Scalia was badly outnumbered [philosophically], so I was mostly assisting him in writing dissents”). He served briefly as a speechwriter for Vice President Dan Quayle, where he had a chance to work with William Kristol (now editor of The Weekly Standard), and he helped Judge Bork, who had failed to win a seat on the Supreme Court, research material for his 1989 book, The Tempting of America.

He arrived at Northwestern University School of Law in August 1990, recruited by Gary Lawson, a friend from Yale and charter member of the Federalist Society who has since gone on to the Boston University School of Law.

For family reasons, Calabresi and his wife, Mimi, and their four children also moved to Boston two years ago; he commutes to Northwestern, where he teaches constitutional and comparative law-though that tells only part of the story. With his Northwestern law school colleague James Lindgren, he helped prepare Hail to the Chiefs, an extensive online project, sponsored by the Federalist Society and The Wall Street Journal, that ranked all the U.S. presidents from 1789 to 2000 (Washington, Lincoln, and FDR took the top slots, though Calabresi argued that Ronald Reagan belonged among them). He is shopping a recently completed manuscript on presidential power, and, with Lindgren, advocating term limits for Supreme Court justices, a position the pair have argued in op-ed pieces and in a lengthy law-review article. “The reaction has been very positive,” says Calabresi about this radical proposal. “People on both the left and right think it’s a sensible idea. It’s unhealthy in a democracy to have high government officials serve for 25 or 30 years.”

Not to be pigeonholed, Calabresi, who today serves as national cochairman of the society, is critical even of the conservative Rehnquist court. “The Supreme Court continues to make significant mistakes,” he says-the most serious perhaps being the decision that awarded the 2000 presidential election to George W. Bush, an “activist decision” that appalls this self-described “moderate originalist.” “It should have been left to the political process,” he insists, though the decision did elevate his preferred candidate to the White House. “It is quite clear that if this was going to be decided at the national level, it should have been handled by Congress, not the Supreme Court.” The man is nothing if not full of surprises.