Police officers carrying Tasers are both more likely to be assaulted and to use force against suspects, a new study suggests.
It was also found they faced twice as many assaults as unarmed colleagues.
Between June 2016 and June 2017, researchers allocated a Taser-carrying officer to 400 frontline shifts.
Use of force was 48 per cent higher among those City of London officers carrying Tasers than their unarmed counterparts.
It was 19 per cent higher among those without a Taser but accompanying a carrying officer.
Six physical assaults against police were recorded during shifts with Taser-carrying officers, compared to just three on unarmed shifts.
In total, over the study period, Tasers were “deholstered” nine times by the examined officers, with suspects shocked on two occasions.
Dr Barak Ariel, from the Cambridge Institute of Criminology, said: “We found that officers are more likely to be assaulted when carrying electroshock weaponry and more likely to apply force. The City of London Police rarely discharged Tasers during the study. Yet the very presence of the weapon led to increased hostility between the police and public.
“The presence of Tasers appears to provoke a pattern where suspects become more aggressive toward officers, who in turn respond more forcefully.”
Study co-author Chief Superintendent David Lawes, from the City of London Police, said: “The use of Tasers have been a proportionate and sensible introduction to policing against a backdrop of unsophisticated terror attacks and an increase in violent crime across London. A number of other forces are interested in replicating the study to add to the evidence base and see whether the experiment produces the same results outside of London.
“Across our force, we will continue to use evidence to define how we target problems, which tactics we should use and how we can ensure policing is efficient and safer for both the general public and our officers.”
Oliver Feeley-Sprague, Amnesty UK’s police and security programme director said the organisation has "serious concerns about Tasers becoming the norm for day-to-day policing, and this study reinforces those warnings around the risks posed by the weapon.”
He added: “Amnesty has always said that Tasers have a place in policing when used in genuinely life-threatening situations. The weapon itself, however, comes with risks – which is why we have always argued for it to be used only in very limited and controlled circumstances by highly-trained and specialist officers."
But the Police Federation of England and Wales challenged the findings.
"When you look at the detail I have some serious concerns about the veracity of the results," said its vice chair Ché Donald.
He added: "The researchers state that during the study there were six assaults on police officers carrying Taser as opposed to three from the unarmed control group. They claim this supports the so called “weapons effect” which states that people can escalate their own level of aggression in response to the sight of a weapon.
“This is a tiny number on which to base such a massive assumption. It must also be recognised that officers who carry Taser – specifically because they do have this tactical option - are allocated and attend more incidents where there is an increased threat of harm or violence. Ergo they are naturally involved in more of these types of incident."