Before joining Urban, Rosenthal practiced tax law in Washington, DC, for over 25 years, most recently as a partner at Ropes and Gray. He was a legislation counsel with the Joint Committee on Taxation, where he helped draft tax rules for financial institutions, financial products, capital gains and related areas. He is the former chair of the Taxation Section of the District of Columbia Bar Association.

Rosenthal holds an AB and JD from the University of California, Berkeley and an MPP from Harvard University.