It has long been possible to stuff one of those solid gold, bling-encrusted smartphones (so beloved of Russian oligarchs, hip-hop crews and Arab millionaires) into a spare sock and whack somebody over the back of the head with it - but now armed response smartphones are available cheaply to the man and woman in the street.

Some companies (and not a few crazed individuals) are turning smartphones into taserlike weapons and dispensers of pepper spray. Some have even tried to turn them into guns.

One such device is the Yellow Jacket (as our American cousins call the common wasp), a smartphone case with a sting in that it also functions as a stun-gun. The co-inventor/developer of the Yellow Jacket, one Seth Froome, came up with the concept after being the victim of a violent street mugging. he says, “We developed the Yellow Jacket to be able to take down a fully grown aggressive adult male.”

Users simply click off safety-mode, press a button on the Yellow Jacket case (which costs US$139) and touch the phone/case against the a perceived human threat. The twin electrodes on the device device then deliver a 650,000 volt bolt of low amperage electricity. Those who have tested it says it hurts a lot at the time and leaves the recipient in considerable pain and with aching, twitching muscles for several days thereafter.

Yellow Jacket says that the shock will bring an assailant to his knees in a couple of seconds, but it is not strong enough to hospitalise him. It also produces some serious looking sparks and a loud crackling noise. The company claims that the device gives victims "a fighting chance" to escape from a threatening situation.

Stun guns, disguised otr not are illegal in some US states (Massachussetts, New York, New Jersey and Illinois for example) but they are legal in many other states although users have to be 18 to buy one. However, as history has shown,in America it isn't that difficult for anyone to get his or her hands on a weapon if they decide they want one and anyway there are already plenty of mobile phones out there that have legal pepper and CS spray cannisters piggy-backed on them.

Indeed, another smartphone case called Spraytect is selling like hotcakes at forty bucks a pop. It is completely legal in the US. Spraytect's website advertising says the spray itself is "special proprietary blend of peppers using one of the hottest habanero peppers as its main ingredient. This same blend is used by Homeland Security, the US Military, FBI Offices, Police Departments as well as Corrections Officers across the United States". A 'must have', obviously.

However, though legal Spraytect cases hey cannot be carried on planes in hand baggage or in a pocket. They have to go in checked-in luggage. Probably with very good reason. Vodka martinis, airplane rage and pepper sprays do not go well together

Both Spraytect and Yellow Jacket cases are available for all popular makes of handset including the iPhone and the Samsung Galaxy.

Meanwhile, lest we over here in the UK start to feel a bit complacent, stun guns (disguised as smartphones or not, are utterly prohibited under the terms of the Firearms Act. Not that a nicety like that will stop the determined nutter.

Earlier this year in Manchester, England, a local cretin was jailed for four years for the possession of four stun guns disguised as mobile phones. They has been imported illegally from China.