Public Aircraft H.R. 2440 Oct. 25, 1994
Public Aircraft are operated by or for a government. The aircraft are operated and controlled by the public agency. In the US, the FAA does not have regulatory authority over the aircraft with two exceptions. The flight operations must still adhere to the Part 91 requirements, calling the tower, airspace, etc. and if the agency accepts compensation from another government agency for transport, that is FAA-controlled. The rest is as was noted by the earlier author. Just a small nit - there is no definition of Public Use that is codified. The only term is Pulic Aircraft as noted in the Law.