Susan A. Johnston is a partner at Ropes & Gray in Boston, Massachusetts where she is the head of the Tax Department. She graduated from Wellesley College and earned a J.D. from Harvard Law School. Her practice focuses on the taxation of regulated investment companies, or mutual funds, and other financial products.

She regularly advises mutual funds and their sponsors and investors on a broad range of tax issues relating to the funds' operations, formation, dissolution, and reorganization. She has served as chair of the Regulated Investment Companies Committee of the American Bar Association Section of Taxation, and speaks and writes extensively on the taxation of regulated investment companies.