George Gallantz, a former Proskauer Rose sports attorney who was instrumental in the merger of the National Basketball Association with the American Basketball Association, died on April 24, the day after his 100th birthday.

Gallantz was the longtime outside general counsel to the NBA from its earliest days, defending the league against lawsuits as it grew dramatically throughout the 1960s and 70s. In particular, he represented the NBA in Robertson v. National Basketball Association, 556 F.2d 682 (2d Cir. 1977), a landmark antitrust case—and one of the first-ever sports merger antitrust cases—where player Oscar Robertson sued to block the merger. In that case, a judge issued an injunction delaying the planned merger several years until 1976. The settlement set the stage for the NBA’s free agency rules for players that are still in use.

Gallantz was the "founding father" of Proskauer’s sports law practice, said sports law group cochair Howard Ganz. He said Gallantz took the practice from a two-lawyer group into one known for winning cases for major sports clients. Proskauer’s sports law practice includes up to 90 lawyers who represent all the major leagues: the NBA, the Women’s National Basketball Association, the National Hockey League, the National Football League, Major League Baseball and Major League Soccer.

"George was the cornerstone of our sports law practice," Ganz said. "But he was also regarded as a wonderful teacher and mentor."

In addition to Ganz, Gallantz helped shape the early careers of NBA commissioner and former Proskauer partner David Stern, NHL commissioner Gary Bettman and New York City Corporation Counsel Michael Cardozo. Cardozo said he wrote his first legal brief under Gallantz’s tutelage.

Gallantz was known for giving younger lawyers important roles. In the Robertson case, for example, Stern and Cardozo argued several motions and took key depositions as associates. Gallantz eventually gave up his position as the NBA’s general counsel to Stern in 1978.

"I’m proud to have known George personally for decades," Cardozo said. "He was my mentor, a wonderful lawyer and friend who believed in giving younger attorneys every opportunity. He was a superb writer and taught me how to craft arguments that got to the point quickly and made legal briefs dance."

At Proskauer, Gallantz, who at one time headed the firm’s litigation department, was known for being a stickler for detail.

"He was sometimes difficult," Ganz said. "He did not suffer fools easily."

Lawyers handling cases under Gallantz were careful not to turn in briefs with mistakes, Ganz said. In one instance, a more junior lawyer bet Gallantz 50 cents he could not find any typos in a brief he’d reviewed numerous times. Gallantz found one in a footnote, Ganz said.

Gallantz "was a great teacher," Stern said. "He was unyielding in his demands that we do excellent research and that we write and then revise and be more succinct. Language was an art that we had to master."

Gallantz retired from Proskauer in 1985 when he reached the firm’s mandatory retirement age of 72, though he continued to work on cases for several years afterward.

Born to Ukrainian Jewish immigrants, Gallantz grew up in East Harlem and the Bronx, where he lived with his family in tenements that lacked hot water. He attended City College before earning his J.D. from Brooklyn Law School in 1935. At the time, the law school was tuition-free.

Gallantz’s legal career began at the New York City Corporation Counsel’s office during Fiorello LaGuardia’s administration, under Corporation Counsel William Chanler. Gallantz worked in the litigation department on cases within LaGuardia’s initiative to root out corruption in city government. There he built his reputation as one of the city’s sharpest trial attorneys, the city law department said.

After a decade with the city, he left for Simpson, Thacher & Bartlett, where he stayed a few years before moving into entertainment law for Paramount Pictures. He then formed a small entertainment firm. Marlon Brando and Mickey Mantle were among his early clients. Gallantz represented the famed ball player in a contract dispute with an agent just after he was signed by the New York Yankees.

Gallantz began doing work for the NBA while he was at Simpson Thacher, defending it against a $3 million lawsuit brought by a former player. He brought the NBA to Proskauer Rose as the firm’s first sports client in the early 1960s.

Though Gallantz was offered the NBA commissioner job himself, he declined more than once.

"He said he would only take it if he could continue being a lawyer," said his son, Michael Gallantz. "He wasn’t into being a businessman or an administrator. But he always wanted to be a lawyer and they wanted him full time."

Outside of work, Gallantz loved the New York Knicks and Yankees. He was a regular fixture at city cultural events with his late wife, Laly.

In addition to his son Michael, Gallantz is survived by a daughter, Judith Coven, two grandchildren and three great-grandchildren.

Funeral arrangements are private. The family will host a public memorial at a soon-to-be-announced date.