Levy also said of Garrett that he "never had a student who made better use of time." As a sophomore at the University of Oklahoma, Garrett became chair of student congress, the University of Oklahoma Student Government Association, a position she held until she graduated. In 1988, she received her law degree from the University of Virginia School of Law. After law school, Garrett clerked for U.S. Supreme Court Justice Thurgood Marshall and for Judge Stephen F. Williams on the U.S. Court of Appeals for the District of Columbia Circuit. She also served as a legal advisor at the Iran–United States Claims Tribunal at The Hague and as legislative director and tax and budget counsel for Senator David L. Boren of Oklahoma. Boren said about Garrett, "If I were to count on the fingers of one hand the people I’ve known with the most remarkable intellect, she would be on that list." Garrett's primary scholarly interests included legislative process, the initiative and referendum process and the federal budget process. Among her prolific writings, she was co-author of the preeminent case book on legislation and statutory interpretation, "Cases and Materials on Legislation and Regulation: Statutes and the Creation of Public Policy" (2014). She was also co-editor of "Fiscal Challenges: An Interdisciplinary Approach to Budget Policy and Statutory Interpretation Stories". Her interdisciplinary scholarship used insights from economics and political science to understand how to design democratic institutions to ensure outcomes more consistent with citizen preferences—and how those preferences might be shaped by the political and legal environments. Garrett was a professor of law at the University of Chicago from 1995 to 1999 and also served as deputy dean for academic affairs. She also taught as a visiting professor at Harvard Law School, the California Institute of Technology, the University of Virginia Law School, Central European University in Budapest, and the Interdisciplinary Center Law School in Israel. Garrett began her tenure at the University of Southern California in 2003 as the Frances R. and John J. Duggan Professor of Law and Vice Provost. Between 2010 and 2015, Garrett served as Provost and Senior Vice President for Academic Affairs, USC's second-ranking officer under USC President C. L. Max Nikias. As provost, she proved a superb administrator with a complex portfolio. In addition to serving as a professor in the USC Gould School of Law, Garrett oversaw the Dornsife College of Letters, Arts and Sciences, as well as the Keck School of Medicine of USC. She also hired Provost Professors and founded the Provost's Postdoctoral Scholars Program in the Humanities.