When Alan Dershowitz was a student at New York's Yeshiva University High School, he was called in by the principal, a rabbi, and given some career counseling. "You have a good mouth on you, but no head," the rabbi said. "So you gotta do something that you need a good mouth for but no brains. Become a lawyer."

He did—and quite a successful, high-profile lawyer too, not to mention a professor at Harvard Law School. Dershowitz defended Claus von Bülow, he defended porn actor Harry Reems, and he defends the First Amendment wherever he believes it is threatened. But there was at least one thing he found indefensible: the criminal lack of a good kosher delicatessen in the predominantly white-bread environs of Cambridge, Mass., where you can get a B.A., an M.A. and an LL.D., but until recently, says Dershowitz, you couldn't get a decent pastrami on rye.

So the 50-year-old attorney listened to his mouth, which longed for the well-remembered delicacies of his Uncle Menashe's deli in their native Brooklyn. He got together with fellow lawyer Marcus Weiss and two dozen limited partners, and they opened up Mavens Kosher Court, a genuine New York-style delicatessen, right on well-pedigreed Winthrop Street, just 150 yards from Harvard Square.

Decorated in rich mahogany paneling with track lighting and upholstered booths, the deli is more than Dershowitz had envisioned originally. "I thought we would have this little hole in the wall," he says. "It never occurred to me that we would have this beautiful place." Since it opened in April, Mavens has hit it big with town and gown. It can serve about 100 diners at a time, and the lines sometimes stretch out onto the sidewalk. When that happens, the waiters pass out pickles to waiting customers.

The clientele includes actor Ken Howard, playwright David Mamet, ex-J. Geils Band rocker Peter Wolf and a couple of local heroes, Celtics president Red Auerbach and old No. 17, John Havlicek. The deli's so-called board of mavens, whose duties are indistinct and not especially time consuming, includes such luminaries as violinist Itzhak Perlman, cellist Yo-Yo Ma, actor Elliott Gould and Alan's mother, Claire.

Mavens serves all the old favorites, from tsimmes (a carrot, sweet potato and brown-sugar combination) to kasha varnishkas (a grain and pasta dish) to ptcha, which Dershowitz describes as "Jewish Jell-O for garlic lovers." The overstuffed sandwiches go for $6.95 or so, and the menu is replete with cutely named entries, including such legal in-jokes as the Chief Justice Burger and Justice Felix' Favorite Frankfurter. To date, the hottest seller is the Talmudic Dilemma, about which the menu says, "If you can't decide, on one hand get a half corned beef, and on the other get a half pastrami." And, triumphantly, there is the Restricted Club sandwich (turkey, corned beef, pastrami, lettuce, tomato and sauerkraut; no bacon). It commemorates the sweet victory of the deli's location: The building once housed the now-defunct Pi Eta Society, which didn't accept Jews as members.

—By Michael Neill, with Gayle Verner in Cambridge