Lawyers rarely get to display their artistic talents. The closest most get to the creative process is drafting a contract for a performer or writer.

Lesley Rosenthal, the chief operating officer of The Juilliard School, is no longer settling for mere vicarious pleasures. The former general counsel for Lincoln Center and one-time litigation associate at Paul Weiss is making her opera debut as the co-librettist (meaning “co-writer,” for the uninitiated) of “Dear Erich,” a jazz opera that premiered Wednesday at the New York City Opera.