Was watching a program about the transport of US convicts by aircraft and bus. Two things struck me. One was what nice up to date trainers some of the cons were wearing. Not that the British prison service is much better big heavy boots ideal for hiding stuff in or dishing out kickings. Some of the other convicts had slipper like footwear. This would be cheaper and lend itself to a lot less mischief.
The other thing was about handcuffs. Because they are intended to be fitted quickly to a struggling suspect conventional handcuffs have very simple locks, that are not that hard to pick. During a long journey cons are bound to fiddle with their cuffs and see if they can open them. This is recognized by the prisoner transport staff, who fit a separate locked cover over the cuffs, known as the black box. There doesn't seem to be total confidence in this measure. High security prisoners are also fitted with special mitts to immobilize their hands.
Suppose we have a more secure cuff, designed to be placed on subjects who are not struggling or who have already been cuffed conventionally. I'm reminded of a sort of cuff I saw once that I was told was German. It was a steel rod bent into a rectangle with a short chain and a padlock at each end. Suppose we modify this basic idea so that the ends of the rectangle are concave to fit the wrists better, and the padlocks are wielded to the frame. The padlocks would be of the crossbolt type rather than those with a hasp, and the gap would be just large enough for the chain to pass through, to reduce the chances of shimming the bolt. When correctly fitted the locks would be on the underside of the cuff and the hands would be held apart so they can't touch.
Hopefully that is clear without me having to sketch it.
John Nystrom writes:- Seems clear to me. We (Indiana State Police) went with hinged cuffs (instead of the chain connection) and put them on with the keyways up and unreachable. They are also easier for us to take off with the keyways up, you don't have to push their hands out of the way to put the key in and turn it.
Your idea will work well for transport if they don't substitute locks with hasps, and they apply them behind the back. I always transported prisoners in my patrol car (no rear cage) in the front passenger seat, cuffed behind the back, seatbelted in. When I worked at the state prison we transported them in a 3/4 ton van, hand cuffed in front with a black box over the keyways, waist chain around them, with a pad lock through the chain and black box. Prisoner and unarmed escort officer on a bench seat with an empty bench seat between them and the armed driver.
In front and the prisoners can too easily get to each others locks. Warded AND guarded locks are the choice for pick resistance.
I think for transport by aircraft etc it is not actually practical to transport prisoners cuffed behind their backs, hence the idea. I think the basic idea has merit. I'll listen to experienced cops like you as to the best way to use it.