Morgan Kousser (pronounced Cow' zer) is the author of The Shaping of Southern Politics: Suffrage Restriction and the Establishment of the One-Party South, 1880-1910 (Yale Univ. Press, 1974) and Colorblind Injustice: Minority Voting Rights and the Undoing of the Second Reconstruction (Univ. of NC Press, 1999), as well as 47 scholarly articles, 83 book reviews or review essays, 26 entries in encyclopedias and dictionaries, 45 papers at scholarly conventions, and 74 talks at universities. Colorblind Injustice was co-winner of the 1999 Lillian Smith Award of the Southern Regional Council and of the Ralph J. Bunche Award of the American Political Science Association. Most of his work has concerned minority voting rights, the history of education, and the legal and political aspects of race relations in the 19th and 20th centuries. From 2000 through 2012, he was the executive editor of the journal Historical Methods. He has served on the editorial boards of The Journal of American History, The Journal of Interdisciplinary History, Social Science History, and Historical Methods.

Kousser has also served as an expert witness or consultant in over 60 federal or state voting rights cases, and he testified before a subcommittee of the U.S. House of Representatives in 1981 and 2019 about the renewal of the Voting Rights Act. He was the principal expert witness on the intent issue for the Mexican-American Legal Defense and Education Fund in the Los Angeles Supervisors' redistricting case, Garza v. County of Los Angeles (1990) and for the U.S. Department of Justice in U.S. v. Memphis (1991). Garza resulted in the election of the first Latino in 115 years to the nation's largest county governing body; the Memphis case resulted in the election of the first African-American mayor in the history of the city. He was also an expert witness for the NAACP-Legal Defense Fund in Shaw v. Hunt (1994), the North Carolina "racial gerrymandering" case, for the Justice Department in its Texas counterpart, Vera v. Richards (1994), and for MALDEF in Cano v. Davis, the 2002 California congressional and legislative redistricting case. Some of his recent testimonies include redistricting cases in Texas, voter ID cases in Texas, North Carolina, and Alabama, and the felony disfranchisement case in Florida. In addition, he was the principal expert witness in all of the cases that have gone to trial under the California Voting Rights Act: Palmdale, Highland, Santa Clara, and Santa Monica, as well as a consultant in 16 other CVRA actions.

In 2008, he published the first comprehensive history of Section 5 of the Voting Rights Act, a 108-page article in the Texas Law Review, and in 2015, an analysis of the largest database ever collected on voting rights cases. In 2011, he became the first professor from the Humanities and Social Sciences Division to win the Richard P. Feynman Teaching Award at Caltech. (Seventeen professors in STEM fields had previously won the award.)

Educated at Princeton and Yale, he has been a visiting professor at University of Michigan, Harvard University, Claremont Graduate University, and Hong Kong University of Science and Technology. In 1984–85, he was the Harold Vyvyan Harmsworth Professor of American History at Oxford University. Since 1969, his primary affiliation has been with Caltech. He retired from teaching at Caltech in July 2020.