Richard G. Lonsdorf, Psychiatry and Law

Richard G. Lonsdorf, professor emeritus of psychiatry and law at the University of Pennsylvania Law School, died of congestive heart failure at the Waverly Heights retirement community in Gladwyne, Pennsylvania, on March 18. He was 93 years old.

Dr. Lonsdorf was born in Scranton, Pennsylvania. He earned his bachelor’s degree from the University of Scranton in 1942. He then attended Penn’s medical school, which is now the Perelman School of Medicine, and graduated in 1946 at age 23. In the aftermath of World War II, he served with the Navy Medical Corps in Fort Worth, Texas. He then returned to Penn to complete training as a psychiatrist and, later, a psychoanalyst. He also ran a private psychiatry practice in his home and at an office in Center City Philadelphia.

He began teaching at Penn’s School of Medicine in 1952. In 1959, he took a secondary appointment at Penn’s Law School, where he helped to develop a course in forensic law that dealt with legal issues relating to the criminal mind. The course became a mainstay of the curriculum, and Dr. Lonsdorf taught it for more than 40 years to generations of Philadelphia lawyers and judges.

In 1982, he was promoted to clinical professor of psychiatry and law. During his time at Penn, he served on the Institutional Animal Care and Use Committee and the Committee on the Chronically Mentally Ill Homeless, a subgroup of the Mayor’s Public-Private Task Force on Homelessness.

Dr. Lonsdorf was one of the pioneering authorities on the use of the insanity defense in criminal cases. He lent his expertise to state and federal lawmakers who were crafting rules for the introduction of such evidence at trial. He often testified in court, including as a consulting psychiatrist in the legal challenges that followed the 1982 conviction of John Hinckley, Jr. for the attempted assassination of President Ronald Reagan. Mr. Hinckley was found to be not guilty by reason of insanity.

Dr. Lonsdorf retired from Penn and took emeritus status in 1993.

He is survived by three sons, George (Deborah Holljes), David (Marilyn Chohaney) and Robert (Lino Aleylunas); four grandchildren; and two great-grandchildren. His wife, Alice B. Lonsdorf, a former assistant dean for alumni affairs at Penn Law, died in 2014 (Almanac April 29, 2014). Donations in his memory may be made to the Sierra Club ( or to the Nature Conservancy (