A teenage boy has been Tasered by officers from Devon and Cornwall Police at Chelfham Senior School near Plymouth during an incident in which he and two other students allegedly assaulted a teacher.
The teacher was treated by paramedics at the scene before being taken to Derriford Hospital with head and chest injuries.
The three youths - one aged 15, two others aged 14 - have been charged with affray and will appear at Plymouth Magistrates' Court on 20 December.
Sophie Khan, director of advice service Police Action Centre, said: "The use of a Taser on this occasion has to be called into question. The police action may have been excessive. The use on children is only allowed if it is the only feasible method of restraining the child."
Located in the village of Bere Alston and owned by the Priory Group, Chelfham is a day and residential school for children aged 7-19 with behavioural, emotional and learning difficulties.
The school described the incident as "an isolated incident on the school grounds and as legal proceedings are ongoing it would be inappropriate to comment further".
So far the Independent Police Complaints Commission is not thought to have been contacted about the Chelfham incident, which took place on 1 December but was only confirmed by Devon and Cornwall police on 7 December.
The Devon and Cornwall Constabulary is already under investigation following the death of Andrew Pimlott, 32, who died when police Tasered him on 18 April this year despite him having poured fuel over his body. Pimlott burst into flames and died in hospital five days later.
Devon and Cornwall used Tasers 65 times in 2011 and in 2012 had to pay £5,000 compensation to a man who was Tasered in a busy pub.
According to the Home Office, almost one child a day is Tasered in the UK by police, including children as young as 11. 12,000 Tasers are available to UK forces and the Police Federation have been reported as requesting this number be raised to 36,000.
Ten fatalities have been linked to Taser use in the UK since the stun gun was introduced in 2004, most recently the death of 23-year-old Jordan Begley in Manchester. In the US at least 500 people are thought to have died as a result of being Tasered and Amnesty has called for a ban on their use against children.