Just put "Taser" into YouTube and you'll see plenty of examples of alleged questionable use, some very disturbing.
So when then Home Secretary John Reid announced plans to expand the number of officers issued with the stun guns in 2007, human rights groups such as Amnesty International saw it as the start of a "slippery slope".
In their view, more police routinely armed with them would mean more widespread use and a greater chance that a weapon designed to deliver pain as a means of control could be used as an instrument of torture.
The Metropolitan Police is one of 10 forces authorised to start training non-specialist firearms officers in Taser use as part of a Home Office pilot scheme.
It is a measure of the controversy surrounding the pilots that, although they were supposed to start in September, the Met did not begin its pilot until November, following objections from members of the Metropolitan Police Authority.
This is a Taser, 50,000 volts, it will be used against you if you do not comply
Police officer to suspect
BBC News joined a police operation in which non-firearms officers would deploy Tasers while making an arrest.
Before the early morning raid police had already decided the man they were after posed a risk to officers, as he had allegedly taken part in a series of violent robberies and was known to have a volatile temper.
Officers of the Met Police's Territorial Support Group (TSG), who had been trained in Taser use, were brought in to back up their colleagues from the Robbery Squad and make the arrest.
Kitted out with full riot gear and shields, officers smashed in the door of the robbery suspect's flat in west London.
The stun guns have changed police tactics in this type of situation. Before they had access to the weapons, officers would have charged inside and subdued their quarry with sheer weight of numbers.
Now, the officers draw their Tasers and call out to the man by name to come to the door of the flat.
The man emerges, clearly startled by the early wake-up and the "in your face" attitude of the police.
As he comes to the doorway, hands on his head as instructed, one officer shouts at him, "Look at the dots on your chest," the man looks down at the red laser sighting dots playing across his torso.
What we have to be very mindful of... is that we don't get complacent
Commander Bob Broadhurst
The same officer explains: "This is a Taser, 50,000 volts, it will be used against you if you do not comply."
The man offers no resistance as he is handcuffed and led away. The whole arrest has taken no more than two minutes.
Sergeant Andy Harding from the Met's TSG, who trains officers in using the stun guns, was on the raid and was pleased with how it went.
He said: "There was no need for officers to go into the premises, there was distance between the officers and the suspect at all times and at no stage was anybody injured as a result of that raid."
Home Office figures say Tasers have been "discharged" or fired 521 times between their introduction in April 2005 and November 2007.
It is too early to say if the pilots will change the way they are used but anecdotal evidence suggests they are popular with police officers.
PC Paul Peversi, who carries a Taser, was called to an incident where a man was armed with a knife.
"His shirt was off and he had a very large kitchen knife. It was pressed against his chest to the extent that it was beginning to penetrate him and he was shouting 'I'm going to kill myself'."
PC Peversi decided the best course of action was to use his stun gun.
He says: "So I took aim and discharged the Taser, he sort of surrendered, threw down the knife so we could then get him some appropriate medical care."
Later, the man who had been "Tasered" by PC Peversi contacted the police and thanked them for their actions, which prevented him from harming himself further.
Talking to officers taking part in a two-day training course at the Metropolitan Police training centre in Gravesend, it is clear Tasers are becoming a vital piece of kit.
But senior officers are aware that if they want to have the option of using them in future they will have to keep a close eye on their use.
Commander Bob Broadhurst, who oversees the Taser pilots for the Met, said: "I certainly don't think we should be going down the line of giving Taser to every officer.
"What we have to be very mindful of... is that we don't get complacent. That we don't start drawing a Taser and using it when actually we should be engaging the brain and talking to individuals...."
The United Nations Committee Against Torture has described the use of Tasers as "'provoking extreme pain", saying it could constitute a form of torture and in certain cases cause death.
And Amnesty International has strenuously objected to their wider deployment, saying they should remain restricted to specially-trained officers, not handed to non-specialists after only two or three days' training.
The Home Office pilots are to last for a year - only then will police and ministers be able to make a judgment about the future use of Tasers in England and Wales.
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