Barshefsky was raised in a Jewish family on the North Side of Chicago, the daughter of Polish immigrant parents: Getzel "Gustave" Barshefsky, a chemical engineer from Rajgród (1912–1995), and Miriam Rosen (1912–2011), a substitute teacher from Łomża.[6][7] Her father's family surname had been Barszczewski (feminine Barszczewska) in Polish.[8] She has an elder brother, Alvin Barshefsky, and an elder sister, Annette Weinshank.[7] In 1968, Barshefsky graduated from Von Steuben High School.[7] In 1972, Barshefsky graduated from the University of Wisconsin–Madison with a bachelor's degree, double majoring in English and political science. In 1975, she earned her J.D. from the Columbus School of Law of The Catholic University of America.
As of June 2012, Barshefsky is a senior international partner at WilmerHale. Her legal practice focuses on international business transactions, commercial agreements, and regulatory impediments to exporting and investment. Specifically, her expertise lies in "crafting market penetration strategies for goods, services, and investment and devising practical solutions to market access barriers". Her clients include Fortune 100 and other multinational companies that services like trade litigation, dispute resolution, and government relations strategies. She also advises foreign corporations on commercial and regulatory issues in the United States.[4]
Barshefsky has written and lectured extensively on both U.S. and foreign trade laws and public procurement regimes. She was a partner at the law firm of Steptoe & Johnson. She previously served as vice chair of the International Law Section of the American Bar Association as well as a member of its governing council and chair of its Publications Committee.