He teaches and researches in the fields of corporate law and corporate governance, with a particular focus on public companies with controlling shareholders, and shareholder activism. Kastiel earned his S.J.D. and LL.M. from Harvard Law School, where he also served as a John M. Olin Fellow in Law and Economics and as a fellow at the Program on Corporate Governance. He also holds an LL.B. degree (magna cum laude) and B.A. degree in economics from Tel Aviv University. Prior to joining Tel-Aviv University, he was a Research Director at the Harvard Law School Program on Corporate Governance, and a Co-Editor of the Harvard Law School Forum on Corporate Governance and Financial Regulation. He also practiced for four years in the corporate group of a top New York law firm, and clerked on the Israeli Supreme Court.