I just snapped that day. What else could I do?

'I FEEL badly let down by the legal system," says Mike Barile. Sitting in a small Italian restaurant in his home city of Dundee, he confesses it has been a difficult adjustment from teacher to criminal.

"I'm ashamed, I'm embarrassed," he says. "But something like one in four male adults by the time they are 22 have a conviction. So I have joined the bottom 25 per cent."

He makes the comment with a rueful grin but, for the first time in this, his first in-depth interview since his conviction for assaulting two 14-year-old pupils, the tension is showing.

"The only way I can live with it is that I know I couldn't assault anyone. I am totally perplexed as to why it reached the stage it did."

It is a nightmare scenario for any teacher. Allegations are made by a pupil, suspension and investigation follows, a court case and criminal conviction are the end result. It also marks the end of his teaching career – a profession to which he has dedicated 28 years of his life.

The former maths teacher's battle to prove his innocence has come to symbolise the problem of growing indiscipline in Scotland's classrooms. The number of attacks on teachers and pupils in schools has risen, according to statistics. Total recorded incidents, including verbal abuse, rose by 4.3 per cent in 2007, according to figures obtained from councils using the Freedom of Information Act. Physical attacks on teachers and pupils rose by 2.2 per cent between 2005-6 and 2006-7. A survey last year by the Association of Teachers and Lecturers revealed primary pupils are more violent than those in secondary. A third of the primary teachers questioned reported violent behaviour such as punching and kicking. That compared to a fifth of secondary teachers, in a survey which questioned 1,000 teachers across the UK.

The questions being asked by teachers and parents across Scotland is why are such violent incidents rising? And what can teachers do to tackle them – and protect themselves at the same time?

Barile was convicted of assaulting two 14-year-old boys in separate incidents in 2008 at Lawside Academy in Dundee. One of the pupils had been misbehaving but reacted badly to Barile making a note about it. The youth demanded to see the note, grabbing it from the teacher's desk, and refused to return it.

Reacting, Barile grabbed the pupil by the neck of his shirt and pushed him back a couple of paces, saying: "I'll put you through the blackboard."

In the second incident another pupil swore at Barile calling him a "walking penis" among other insults.

Told to stay behind after the class, the pupil attempted to exit when the bell rang but Barile pinned him against the wall by putting his forearm across his chest to prevent him leaving.

Those incidents led to the former teacher being prosecuted, much to his astonishment and the astonishment of many in the profession. How, they asked, were teachers expected to cope with increasingly badly behaved youngsters?

Although found guilty, the sheriff admonished Barile. Appeal judges did not quash the conviction, but they questioned why he was ever prosecuted, describing the pupil behaviour Barile was subjected to as "disgraceful".

Last week, in a separate appeal against the sentence, Barile won an absolute discharge which means, although the conviction is not quashed, it is deemed not to be a conviction except in very limited circumstances. It means he does not need to declare it and can pursue occupations which might otherwise have been barred to him.

It may be regarded a Pyrrhic victory for a man who has been forced out of a profession to which he had dedicated almost three decades.

Barile clearly still cares deeply about his former colleagues and their charges. He says: "I would love to see schools have up-to-date facilities, CCTV cameras in schools. Who's got anything to be afraid of except badly behaved kids?"

He has agreed an out-of-court settlement with Dundee City Council which prevents him talking about his time working as a teacher for the local authority, or the incident which led to his dismissal and sparked the court case.

He does talk about the assault on him earlier in his career by a pupil at Madras College in St Andrews, an incident which he believes marked him out as an easy target for other youngsters at that school.

"I was his register teacher and asked him where his school uniform was and he said it was in the wash," he recalls. "What we, as teachers, were encouraged to do was send them down to the office of the deputy head. But he refused to go and, as I turned to walk back into the classroom, he kicked my heels to trip me up – I couldn't believe it."

As he tells this story, Barile is still clearly astonished by this aggressive behaviour. Although he comes across as a confident, almost bullish man, it is clear, despite being physically capable of protecting himself, he was afraid.

"I stumbled," he says, "turned around and he squared up to me, right in my face. What he was doing was trying to provoke a reaction. I just stood motionless.

"I could feel his breath, he was a fifth year and probably an inch taller than me. I was terrified. Eventually he just walked away but, for one horrible moment, I thought he was going to headbutt me, and the thought went through my head, what was I going to do about it?"

He still doesn't have an answer to the dilemma of how a grown man in a position of responsibility should react to a person who may have the physical attributes of a man but is still a minor.

He reported the incident to his headteacher but, next day, the boy was back in school and Barile was due to teach him later in the day.

"I didn't want to be in the class with him back in until something was resolved," he says. "I phoned the school and asked what he had done, and basically was told not to worry about it.

"At that point I said I wasn't accepting this."

After the phone call, he ensured he had cover for his class and signed out of the school saying he was unable to work for health and safety reasons, and was promptly suspended.

"I just snapped that day, it just culminated in frustration, what else could I do?"

After nearly a year of disciplinary hearings and eight months of suspensions, Barile was only officially reprimanded by Fife Council for his criticism of the school, and he has taken comfort in that.

It was a frustration, he says, borne out of an inability to act against bad pupil behaviour. "The classroom teacher's power has been eroded in a lot of classrooms in Scotland. I'd had authority to detain pupils over lunchtime and interval, to decide how many lines they were given, and that was taken away. The attempt was to depersonalise it."

The idea at the time was to prevent the issue escalating into a vendetta between a particular teacher and child – to have the entire school staff united in sanctions against bad behaviour. However, says Barile, it simply resulted in no action being taken.

He says with clear exasperation: "If they find nothing happens to them, then you cannot make them do anything.

"It is perfectly normal for young people to push the boundaries but they need to have consequences."

Barile also laments the trend for disaffected youngster to be effectively rewarded for misbehaviour with trips to Outward Bound-type centres.

"They misbehave and they get a trip out of a classroom on it – they pick up very quickly on that.

"When I started teaching it was unheard of for a pupil to just walk out, now it's 'my social worker told me to avoid conflict', so they just go out, have a smoke in the toilets, text their pals and come back the next day as if nothing ever happened. What message does that send out to everyone else? We are running out of sanctions."

Barile believes senior management in schools have to back their classroom teachers and trust them to discipline unruly youngsters.

Although he agrees he has seen the behaviour of pupils deteriorate substantially over his 28-year teaching career, he does not blame the children.

He says: "I remember the time when it was few and far between to be told to f*** off. It's part of everyday language in schools now.

"But now senior management just say to the children, 'did you direct it to Mr Smith?' and they say 'no, I just said it' and they are told 'that's okay then'.

"We don't have zero tolerance any more, we have infinite tolerance – whoever said that had it in a nutshell."

Barile is delighted with the absolute discharge handed down by the Justiciary Appeal Court on Thursday, as it will allow him to work with young and vulnerable people in a charity connected with Dundee United Football Club where he sits on the board as the fans' representative – although he will technically still have a criminal record.

Although he has no plans to return to teaching, it is a loss he feels keenly. "It's really sad. I have enjoyed teaching. Seeing a pupil achieving something they didn't think they would be able to do, and the satisfaction you will get from helping someone – I will miss that."

However, he feels he would be too open to future unfounded allegations. "I can never go back to teaching because I feel so vulnerable. Kids make false accusations, to get out of trouble – that's what they do – divert attention away from their own misdemeanour."

If there is one saving grace, it is his hope that his legal battle will have set a precedent which will prevent prosecutors taking action on an incident a non-teacher would never have faced court over.

He says: "If there is any real good out of it then, hopefully, no-one else will have to go through it." And after briefly betraying his sadness, he dons his cheerful demeanour again. To the wider world, Mike Barile has no intention of showing his scars.