Mr. Nussbaum worked for the firm Cowan Liebowitz & Latman. His specialty was intellectual property and copyright. His clients include authors, performers, playwrights, production companies, composers, artists, literary agencies and heirs or estates owning or controlling literary or other intellectual properties. Among the theatre artists he counseled were composers Lynn Ahrens and Stephen Flaherty, director Jerry Zaks, actor Brian Stokes Mitchell and the Roundabout Theatre Company.
He also was the owner of the Hamptons book store chain BookHampton, which has locations in East Hampton, Sag Harbor, Southhampton and Mattituck. Mr. Nussbaum bought the chain of independent bookstores with his wife, Charline Spektor, 12 years ago when the original owners retired. Spektor survives him.
