Schwartz was defense counsel for comedian Lenny Bruce, who was arrested in 1964 and charged with obscenity in connection with his standup routine at Cafe Au Go Go, a Greenwich Village nightclub.[2]
He formed a law partnership with Edward I. Koch in 1965. Appointed Corporation Counsel when Koch became New York City mayor in 1978, Schwartz was credited with revamping the corporation counsel office, which was in disarray as a result of the city's fiscal crisis. Beyond his professional relationships, Schwartz was a close friend and adviser to Koch.[3] Schwartz later said, "Ed Koch and I never had an argument and we never had an uncomfortable day with each other."[4]
Schwartz presided over a legal dispute between authors J. K. Rowling and N. K. Stouffer. Stouffer alleged that Rowling had stolen material from her 1984 works The Legend of Rah and the Muggles and Larry Potter and His Best Friend Lilly.[5] In 2002 Schwartz ruled that Stouffer had lied to the court and doctored evidence to support her claims, fining Stouffer $50,000 for a "pattern of intentional bad faith conduct."[6]