In 2007, in an unusual move for a senior corporate lawyer, he left Cleary Gottlieb and became the chief of staff for the Joint Committee on Taxation, a nonpartisan joint congressional committee that helps lawmakers on prospective tax policies.
But he grew frustrated with the slow pace of the legislative process and left the committee in 2009 to join the law school faculty at U.S.C., where he taught tax law. He also pursued his love for photography, hiking and long-distance bicycling, which took him across the United States, Canada and Europe.
In addition to his mother, Mr. Kleinbard is survived by his wife, Norma Cirincione, with whom he no longer lived; his son, Martin; his sister, Kathy Heinzelman; his brother, David; his partner, Suzanne Greenberg; and a granddaughter.
Mr. Kleinbard submitted the manuscript for a book to his publisher the day before he went into the hospital for surgery in March, said Leslie Samuels, a senior counsel at Cleary Gottlieb who had worked with Mr. Kleinbard there. The book, titled “What’s Luck Got to Do With It?,” explores the role luck plays — whether through inherited wealth, geography or racial heritage — in worsening inequality.
Mr. Samuels recalled how Mr. Kleinbard would roll his eyes at how many of his wealthy clients were oblivious to their good fortune. He recalled Mr. Kleinbard saying: “They’re not so smart — they are just lucky. I was lucky.”