From Monday, the Metropolitan Police will issue Taser stun guns to previously unarmed officers, becoming the 10th force to join the Home Office pilot. To demonstrate the benefits, the Met opened its training centre to the media last week.
By Victoria Bone
How do you stop a man with adrenaline surging through his veins and a knife in his hand?
After you've used every possible means of restraint, what is left?
That's the dilemma the police face every day and that's why they say they need Taser stun guns.
Pc Simon Ashton, a City of London officer, said: "We use what we call pain and compliance techniques, but we deal with people every day on whom that doesn't work.
"It's fight or flight, the rush of adrenalin. It gives them a lot of strength and they can fight against us.
"So if we want to put handcuffs on them, what do we do?"
Taser works by producing neuromuscular incapacitation (NMI) - disrupting signals from the brain to the muscles causing temporary paralysis.
Tasers are yellow precisely so they are not confused with a gun
Pc Ashton, who is on secondment to the Metropolitan Police and involved in Taser training, says it makes the muscles "freeze and tense", forcing the subject into a "plywood state".
He or she then falls over.
Taser generates 50,000 volts, although it is actually the amps delivered, not the voltage, that cause NMI.
Police stress that a household plug carries 13 amps, while Taser delivers 0.0021 amps.
It does this via two probes which are fired on wires into the subject. However, they don't need to pierce the skin and will work through thick clothing.
The initial disabling effect lasts for five seconds, but the probes remain attached so, if the person continues to resist, another burst can be delivered.
"We tell them they will come to no further harm if they comply with us," Pc Ashton said.
A major part of Taser training is learning what to say and, from the moment it is pulled, the officer is constantly talking.
Two probes are fired at the subject to deliver the shock
The subject is told the device carries 50,000 volts and warned to look down at their chest at the red laser sight dot.
Then they are told that if they refuse to comply they will feel the full force.
The police hope the mere presence of Taser will be effective in many cases - what they call the power of "the differentiated use of force".
"The people we deal with day in, day out see this bit of kit and know what it does," Pc Ashton said.
"It's a show of strength and it has a psychological effect that stops them in their tracks. The other psychological effect is from the red dot. Everyone seems to know what that means."
Officers can also "spark" Taser without firing it, producing a loud and threatening electrical crackle.
"But if the psychological effect doesn't work we have the physiological.
"And you can't fight it. It doesn't matter what drugs or alcohol you've had, it will freeze your body if it's used correctly."
'No lasting effects'
But the million dollar question - is it dangerous?
Amnesty International said the weapons have been linked to more than 70 deaths in the US, while the Canadian Broadcasting Corporation has reported that up to 18 people have died in Canada since 2003 after being stunned by a Taser.
Officers must justify any force they use, including Tasers
But, according to UK police, there have been "no severe or adverse reactions" since Taser was introduced in 2003.
Pc Ashton said: "There are no recorded incidents of Taser causing the death of anybody.
"It definitely hurts but, unlike the restraint tactics we use which can cause broken bones or torn tendons, there are no lasting effects and you make a very quick recovery.
"There is a risk someone could fall over and smash their head, but is there not the chance that could happen with the tactics we use at the moment?"
Wherever possible, subjects are shot in the back to avoid accidentally hitting the face or genitals.
Pacemakers are not a problem as they are easily able to withstand the amount of energy delivered.
But guidelines do warn that people of particularly small stature or small children could be at greater risk because their heart is not protected by as much overlying muscle.
"Of course, there are circumstances in which we wouldn't use it. It could set off an explosive, for example, but it's about having a range of options," Pc Ashton said.
As of today, previously unarmed Metropolitan Police officers will carry Tasers.
They will join colleagues from nine other forces involved in the Home Office's pilot of the devices by non-firearms specialists.
The Met officers are all members of the Territorial Support Group (TSG) who face violence, conflict and weapons in their work. Eventually, 734 TSG officers will pass through Taser training at the Met's specialist centre in Gravesend, Kent, but at any one time only six will be on shift carrying them in the capital.
Trainees are put into realistic situations to test their new skills. These are created in a small, but crime-ridden "town" complete with houses, tube trains and burnt out cars on site.
They also practise with armed and moving targets and on firing ranges.
Last week, the Met opened the training centre to the media to demonstrate what goes on and why they believe the controversial new device is needed.
Pc Ashton said: "In recent years we have seen an increase in violence towards the police, but this piece of kit is not just about protecting officers.
Police practise hitting targets with Tasers on a firing range
"It's about protecting the people we're protecting ourselves against. We are using less force against them."
At present, police have a number of weapons at their disposal - batons, metal bars, CS gas and their own feet, fists and brute strength.
But all of these require close proximity to the subject - often a risky business - and may still not be enough.
"We can try the Metropolitan Police pyramid display team as I call it and all pile on, but there's a real problem with that in terms of public perception," PC Ashton said.
"There's also a high risk of someone suffering positional asphyxia.
"So we have Taser. It's going to allow our officers the first chance ever to deal with someone at distance, much like a firearms officer.
"Only this bit of kit can't kill and is unlikely to seriously maim."
Part of Taser's appeal in the government's eyes is its accountability.
Officers must sign out each Taser cartridge they use and every one has a unique serial number and barcode.
When a cartridge is fired it sprays out 20 to 40 AFIDs - anti-felon identification discs. These are tiny circles of paper which also carry the cartridge's serial number. These can be retrieved later to show where Taser was fired and which cartridge was used.
Each Taser cartridge has a unique serial number and barcode
Finally, each Taser is designed to automatically record when and for how long it was used. It stores the last 1,500 firings.
"This is the most accountable piece of equipment the police have today," Pc Ashton said.
The Association of Chief Police Officers (ACPO) says it fully supports the use of Taser by firearms officers in situations "where there is otherwise a real risk that someone may have been shot and killed".
But Chief Constable Charlie Hill said ACPO was reserving judgement on Taser's use by non-firearms officers until the results of the pilot have been analysed.
The Metropolitan Police Authority, an independent statutory body which scrutinises the work of the Met Police, has expressed concern over Tasers.
It reluctantly supported the expansion of Taser use by the Met, but deputy chairwoman Cindy Butts said:
"We remain worried about the message this sends out to London's communities about the escalation of confrontation and need further reassurance that vulnerable people who may behave differently - the young, old and those with disabilities - will not be adversely affected."
I have recently moved from South Yorkshire police to Western Australian police where they use tasers as one of their force options. The taser is a good, useful bit of equipment, but needs to be used in a controlled, professional and closely monitored way.
Through training and strict monitoring I think it will prove to be a useful tool that will help protect the general public and make people think twice before offering violence in the presence of the police.
stephen moffatt, Perth Australia
I was tasered by police in the USA about 3 years ago during an incident that I was since cleared of. To say that it hurts is an understatement. I felt like being stabbed by 1000 sewing needles at once whilst dancing to nu-rave. I didnt like it.
Tom Horn, Tranent
I grew up in England, and just like everybody else of my generation, I was taught that a policeman is your friend. I don't want to disillusion you, but a taser is a lethal weapon - it's just another word for gun. We're still reeling as a nation feeling the shame of a Polish immigrant being tasered recently at Vancouver International Airport. It wasn't necessary, and the man died.
Philip Renouf, Victoria, BC, Canada
Thank God it can stop criminals in their tracks, they are everywhere here in Manchester! I feel so sad to see police officers here cowering from criminals, this will make our offices a bit more like the American heroic police; so you have all my encouragement.
Jack Ek, Manchester
I think two things are needed, 1. more research should be done on affects of 50000 volts to vulnerable people such as pregnant women, children, pacemaker users and other people with health problems, and that 2. only very highly trained police officers should ever be able to use them under strict guidelines - after all just look at what happened in a Canadian airport recently.
Marc, London, UK
Tasers for the Police. About time too! I have been sick to death of reading or seeing reports of thuggish louts resisting authority with impunity. To see a female Police Constable confronting a non-compliant out of control body built thug without any form of real defence herself is, for me a member of the public, a no-go area!
Martin, Crawley UK
I think these things are dangerous even in a police officers hands. If those spikes for some reason hit a person in the head it would no doubt be serious if not fatal.
M D Ellis, Leicester England
It should be part of the Taser training for the trainee Police Officer to receive a Taser shock. Thus, they might think twice before Tasering. 50,000 volts electric charge is too high and there have been deaths due to Taser shots, so there's a need to make it less intense. Also to consider is Tasers going into wrong hands. Criminals will be more trigger friendly with Tasers compare to guns.
I am a serving Police Officer, not a member of any specialist team - just a response Officer. The wider introduction of the Taser is long overdue. We are the people who need to be issued this equipment as a matter of urgency. We are the ones who go to violent domestic disputes, often alone, and often without any back-up.
A taser is a potentially lethal weapon and treated as such if the police come across a member of the public with one, yet they are going to allow non-firearms trained officers out onto the street with them? This is madness, such weapons should be restricted to officers who are qualified to use firearms. We have already seen more than a few incidents in the USA which have resulted in death as well as inappropriate use.
concerned, chelmsford essex
It makes me angry just reading about this! How can this once peaceful land end up like this. I blame the Government for it's heavy-handed approach, lack of respect for peoples rights and freedoms and basically creating a them and us culture. It's no wonder the average man reacts and resists the oppressive acts of this state!
Will this Government never learn?!!