Drawing from his experience in clinical psychiatry and the treatment of substance use disorders, Nathan is a vocal physician advocate of cannabis legalization. He has published numerous articles on the topic. Nathan was one of the founding steering committee members of New Jersey United for Marijuana Reform, speaking at their televised launch in early 2015. He was the first physician in New Jersey history to testify about marijuana legalization at the state legislature later that year. In 2016, Nathan founded Doctors For Cannabis Regulation, which advocates for the legalization, regulation and taxation of marijuana. He wrote the organization's “Declaration of Principles,” which was signed by number of nationally prominent physicians, including Joycelyn Elders, Andrew Weil, Chris Beyrer, David Lewis, and Lester Grinspoon.
Other selected publications and projects
In archeology, Nathan published an analysis of a proto-cuneiform tablet dating to the Jemdet Nasr period of Mesopotamia, which included the discovery of a previously unknown numerical sign. In numismatics, Nathan proposed that the first coins minted in the Western Hemisphere feature a Hebrew letteraleph, suggesting direct evidence for a Jewish presence or influence in the New World as early as 1536. He noted that nearly all of the coin dies prepared under the tenure of the Mexican Mint's first assayer use this purported aleph symbol in place of the Christiancross potent mark found almost universally on medieval Spanish and Mexican coinage. Nathan also considered possible Jewish family connections to the known early Mexican mint workers. While researching the history of early animation, Nathan reconstructed the lost “Encore” sequence from Winsor McCay’s animated filmGertie using original drawings from 1914. With animation historian Donald Crafton, he coauthored an article about the structure and history of Gertie. Nathan initiated a restoration of the entire film and a reconstruction of McCay's original vaudeville performance of Gertie. Crafton, Nathan and Marco de Blois of the Cinémathèque québécoise worked with a team of professionals from the National Film Board of Canada to complete the project, which premiered live during the closing ceremony of the 2018 Annecy Film Festival in France. Publishing in the Princeton Alumni Weekly, Nathan was the first to identify all 24 known members of Princeton University’s 1869 football team, who participated in the first intercollegiate American football game. He published biographies and photographs of all the known players and shared his research into the possible identity of the unknown 25th player.
Awards and honors
In 1990, Nathan received Princeton's Charles M. Cannon Memorial Prize for his senior thesis entitled Web Repair in Several Species of Orb Weaving Spiders. In 2007, Nathan won the Odesser Award for Outstanding Contribution to Judaic Numismatics and Exonumia for his article on early Mexican coins. In 2012, Nathan was elected as a Distinguished Fellow of the American Psychiatric Association.