Cases involving the FDCA and other federal food, drug, and cosmetic laws can generally be found in the same sources and using the same techniques as other cases. For information on researching U.S. case law generally, see Georgetown Law Library's Case Law Research Guide.
Specifically, cases on this subject can be found in the CCH Food, Drug, and Cosmetics Law Reporter (KF3868.5 .C6 1963; print cancelled in 2008), which is available on VitalLaw.