Teachers who use force to restrain violent special needs pupils should be given extra protection against allegations of assault, according to a teaching union.

The NASUWT said too many teachers in special schools find themselves in trouble for simply carrying out their jobs in what are “difficult and challenging” environments.

It comes after a senior teacher was cleared of misconduct charges by a General Teaching Council for Wales (GTCW) disciplinary panel last week in what the union called a “landmark case”.

David Kevin Thomas, a former craft design technology teacher at Ysgol Bryn Castell special school in Bridgend, was accused of acting outside the school’s behaviour policy by disciplining a 15-year-old pupil when it was not his responsibility to do so.

The boy, referred to as pupil A, claimed Mr Thomas had thrown him to the floor while disciplining him, leaving him with facial injuries and marks to his body.

But Mr Thomas maintained he had tried to restrain pupil A after he became aggressive and accidentally fell on top of him when his knee buckled.

Mr Thomas was suspended and later dismissed for gross misconduct after an internal investigation, but was cleared of assault charges after a criminal hearing at Bridgend magistrates court.

The GTCW panel found the charges against Mr Thomas were not proven, and said it made “no adverse findings” against him.

Speaking after the case, David Browne, the NASUWT official who represented Mr Thomas, said: “In schools with behaviour issues you expect there to be many instances where teachers need to restrain a pupil. But a number of experienced special needs teachers are finding themselves suspended, disciplined or up before their professional body simply for doing their job and using their training.

“There has to be a greater respect for their professional judgment and a greater degree of protection, otherwise teachers will refuse to work in these risky environments.”

The Assembly government has recently consulted on new guidance safe and effective intervention in schools. But, as TES Cymru reported last week, the Children’s Commissioner for Wales has criticised it as “overly punitive” and “draconian”.

Although Mr Thomas, aged 52, has managed to find another teaching job, he said he still faced financial misery and health problems as the result of the case, which had “blown his world apart” and left him “devastated”.