Last week, the New York Attorney General’s office sent Madison Square Garden Entertainment a letter demanding answers. The state’s top law enforcement agency wants to know more about how the company operating Radio City Music Hall and the storied arena where the NBA’s Knicks play uses a face recognition system to deny entry to certain people, and in particular lawyers representing clients in dispute with Madison Square Garden. The letter says that because the ban is thought to cover staff at 90 law firms, it may exclude thousands of people and deter them from taking on cases “including sexual harassment or employment discrimination claims.”