A Harvard Law School professor best known for defending the man who leaked the Pentagon Papers and for helping parents sue chemical companies in a case popularized by the film "A Civil Action" has a new cause: poker.

Charles Nesson wants governments to relax restrictions on poker players. He has formed the Global Poker Strategic Thinking Society with some of his students to promote poker as a fun learning tool and to redefine it as a game of skill, rather than a game of chance.

"I'd like to legitimate poker as an educational instrument," Nesson said. "It's a great way to learn and practice the skills of seeing what things look like from another person's point of view."

Locally, Nesson wants to loosen Massachusetts' limits on small-scale poker tournaments. He's still angry that an annual student-run charity tournament was canceled last spring because organizers did not know they needed a permit.

He's also lobbying Congress to overturn or amend a U.S. law that effectively bans online gambling.

"Obviously the distinction is that in games of chance, you're not using your brain," he said. "You may be entertaining yourself but you're not really engaging in a developmental activity, whereas (in) games of skill you develop skill. You learn to be smart, you learn to win."

Nesson rose to fame by defending Daniel Ellsberg, who in 1971 leaked to the media the "Pentagon Papers," secret documents that indicated the government deceived the public about whether the Vietnam War could be won. Ellsberg faced up to 115 years in prison, but the charges were dismissed because of government misconduct against him.

Later, attorney Jan Schlichtmann persuaded Nesson, an expert in evidence, to join his legal fight against chemical companies whose alleged polluting was suspected of causing leukemia among children in Woburn. Jonathan Harr's book, "A Civil Action," documented the case and was later turned into a film starring John Travolta.

About a month ago, Nesson and several dozen students formed the poker society. Besides the legal arguments, they want to promote what they say are academic aspects of poker. They are planning academic seminars on poker for youngsters.

They created a Web site and are helping organize chapters at Yale, Brown, Penn State, Stanford and other universities.

Andrew Woods, a third-year Harvard Law student who is head of the founding chapter, is planning a Harvard-Yale poker match the night before The Game, the annual November meeting of the universities' football teams. He said USC and UCLA poker clubs will square off before those schools take to the gridiron next month. They are exhibition tournaments, with no money wagered, he said.

Woods envisions a "March Madness" tourney next spring to coincide with the NCAA basketball tournament.

"I'd like to be able to talk about poker and not have eyebrows raised," said Woods, 24. "People tend to associate poker with craps and roulette and slot machines and the Wild West."

Nesson said the Poker Players Alliance, a 2-year-old lobbying group that claims to represent 809,000 poker enthusiasts nationwide and gets funding from commercial gambling companies, provided $10,000 to support a seminar last spring where he, students, academics, pros and lobbyists discussed strategies.

Woods said he is starting a fundraising effort to help his poker society expand to hundreds of campuses, and he may ask the alliance to contribute.

Nesson and Woods were on Capitol Hill last week, joining the alliance in pressing Congress to consider several new bills that would exempt poker from the Internet gambling law. The alliance estimates there are between 15 million and 23 million U.S. Internet poker players.

Supporters of the ban say Internet betting can be addictive and potentially drain people's savings. U.S. Sen. Jon Kyl, R-Ariz., is a leading proponent of preserving the ban. Without it, "minors are able to gamble from their own homes," Kyl spokesman Ryan Patmintra said.

The Rev. Richard McGowan, a Boston College professor and gambling expert, said he supports the ban because online gambling entices underage people and can lead to addictions. McGowan said he's skeptical of Nesson's efforts.

"It does seem like it's glorifying gambling," he said. "The industry is always trying to argue that these are games, not gambling."