Mr. Greenstein is a real estate partner in the New York office of Seyfarth Shaw LLP. He focuses his practice on cooperative and condominium law and provides counsel to approximately 160 cooperatives and condominium buildings located in New York City. Prior to starting his practice, Mr. Greenstein served as a New York State Assistant Attorney General in the Real Estate Financing Bureau, Cooperative and Condominium Section.

Mr. Greenstein is currently Co-chair of the New York State Bar Association Committee on Condominiums and Cooperatives and previously served as a member of the New York State Bar Association's liaison committee with the Department of Law (Attorney General's Office) on co-op and condo conversions. He is a frequent contributor to, and often quoted in, publications such as The New York Times, addressing issues relating to cooperative and condominium law. In addition, Mr. Greenstein has written articles for or lectured and conducted seminars and workshops on the subject of cooperatives and condominiums at the Real Estate Board of New York, CNYC, The Cooperator, HABITAT Magazine, New York University’s Continuing Education Program and the office of the Attorney General.