32 CFR 634.49 - Standards for impoundment.
(a) POVs should not be impounded unless the vehicles clearly interfere with ongoing operations or movement of traffic, threaten public safety or convenience, are involved in criminal activity, contain evidence of criminal activity, or are stolen or abandoned.
(b) The impoundment of a POV would be inappropriate when reasonable alternatives to impoundment exist.
(1) Attempts should be made to locate the owner of the POV and have the vehicle removed.
(2) The vehicle may be moved a short distance to a legal parking area and temporarily secured until the owner is found.
(3) Another responsible person may be allowed to drive or tow the POV with permission from the owner, operator, or person empowered to control the vehicle. In this case, the owner, operator, or person empowered to control the vehicle will be informed that law enforcement personnel are not responsible for safeguarding the POV.
(c) Impounding of POVs is justified when any of the following conditions exist:
(1) The POV is illegally parked -
(i) On a street or bridge, in a tunnel, or is double parked, and interferes with the orderly flow of traffic.
(ii) On a sidewalk, within an intersection, on a cross-walk, on a railroad track, in a fire lane, or is blocking a driveway, so that the vehicle interferes with operations or creates a safety hazard to other roadway users or the general public. An example would be a vehicle parked within 15 feet of a fire hydrant or blocking a properly marked driveway of a fire station or aircraft-alert crew facility.
(iii) When blocking an emergency exit door of any public place (installation theater, club, dining hall, hospital, and other facility).
(iv) In a “tow-away” zone that is so marked with proper signs.
(2) The POV interferes with -
(i) Street cleaning or snow removal operations and attempts to contact the owner have been unsuccessful.
(ii) Emergency operations during a natural disaster or fire or must be removed from the disaster area during cleanup operations.
(3) The POV has been used in a crime or contains evidence of criminal activity.
(4) The owner or person in charge has been apprehended and is unable or unwilling to arrange for custody or removal.
(5) The POV is mechanically defective and is a menace to others using the public roadways.
(6) The POV is disabled by a traffic incident and the operator is either unavailable or physically incapable of having the vehicle towed to a place of safety for storage or safekeeping.
(7) Law enforcement personnel reasonably believe the vehicle is abandoned.