The story
On November 1, 1919, San Francisco Police officer (and future barnstormer) Ivan R. Gates became the first to transport a prisoner by air, one James Kelly (convicted of carrying concealed weapons), from Alameda to San Francisco.
Prior to the existence of JPATS, the air transport of federal inmates over long distances was complicated. The process required an escort by two U.S. Marshals, accompanying the inmate on a regular passenger airplane. This posed numerous problems, including danger to civilians, a backlog of marshals needed to perform such escorts, and a high taxpayer expense.
On August 20, 1985, the U.S. Marshals were offered a transfer from the Federal Aviation Administration (FAA) of a Boeing 727 aircraft. Though no purpose was originally designated for this plane, one official had the idea of using it for the mass transportation of federal inmates. JPATS' predecessor was the National Prisoner Transportation System of the U.S. Marshals Service.
The airline ultimately improved the efficiency of inmate transportation and made the sight of a shackled commercial airline passenger largely a thing of the past. For a plane full of 200 inmates, only 12 marshals are required. Marshals are trained with aircraft emergency procedures very similar to those flight attendants learn to protect the aircraft's occupants, though no data shows the efficiency of this training.
From Wikipedia’s article on Justice Prisoner Air Transportation System, shared under CC BY-SA 4.0.3