In 1974 Schwebel became Deputy Legal Adviser to the U.S. Department of State where he assisted in the formulation and implementation of U.S. foreign policy. During his service as Deputy Legal Adviser, he participated as Associate Representative, Representative Counsel and Deputy Agent of the United States in various cases before the International Court of Justice including: Interpretation of the Agreement of 25 March 1951 Between the World Health Organization and Egypt (1980), United States Diplomatic and Consular Staff in Tehran (1979–1980) and, while serving as Assistant Legal Adviser for United Nations Affairs, Certain Expenses of the United Nations (1962).[14]