Beginning in 1968, Loewen testified as a statistician and social scientist in a variety of cases relating to jury exclusion by race and age, the voting rights of racial minorities, employment discrimination, the provision of city services like street paving and garbage pickup, unequal taxation, and bias in “standardized” tests. Because he taught “Statistics and Social Research” to undergraduate sociology students, he became good at explaining basic concepts and tests to non-sociologists, such as lawyers and judges. In 1982, he published Social Science in the Courtroom: Statistical Techniques and Research Methods for Winning Class‑Action Suits (Lexington, MA: D. C. Heath/Lexington Books, 1982). At the time, Loewen had probably consulted or testified using a wider variety of statistical techniques than anyone else.