Herbert Leonard Ley, Jr. (September 7, 1923 – July 22, 2001) was an American physician and government official.
He attended Harvard College from 1941-1943, and returned there after World War II, where he received his M.D. degree, cum laude, in 1946. In 1951, he earned an Master of Public Health degree from the Harvard School of Public Health. From 1951 until 1958, he worked with the Army Medical Service Graduate School in rickettsial disease research, the Office of the Surgeon General, and as an epidemiologist in Korea and Vietnam.
In 1958, he accepted a position as Professor of Bacteriology and Chairman of the Department of Bacteriology, Hygiene, and Preventive Medicine at George Washington University. In 1963, he was appointed Associate Professor of Epidemiology and Microbiology at the Harvard School of Public Health, and became chairman of the Department in 1964. In September 1966, Ley took a leave of absence from his position to become Medical Director at the Food and Drug Administration
On October 21, 1969, Abbott Laboratories reported that the artificial sweetener cyclamate (in a saccharin-cyclamate mixture) had caused liver tumors in rats. Cyclamates were removed from the list of Generally recognized as safe (GRAS) ingredients at Dr. Ley's direction on October 30, 1969.
Frustrated with the red tape and conflicts with pharmaceutical companies, Ley resigned his position at FDA on December 11, 1969.
In the San Francisco Chronicle of January 2, 1970 he is quoted as saying "The thing that bugs me is that people think the FDA is protecting them. It isn't. What the FDA is doing and what the public thinks it's doing are as different as night and day.”
His activism earned him a spot on the master list of Nixon political opponents.