More and more US schools have police patrolling the corridors. Pupils are being arrested for throwing paper planes and failing to pick up crumbs from the canteen floor. Why is the state criminalising normal childhood behaviour?

The charge on the police docket was "disrupting class". But that's not how 12-year-old Sarah Bustamantes saw her arrest for spraying two bursts of perfume on her neck in class because other children were bullying her with taunts of "you smell".

"I'm weird. Other kids don't like me," said Sarah, who has been diagnosed with attention-deficit and bipolar disorders and who is conscious of being overweight. "They were saying a lot of rude things to me. Just picking on me. So I sprayed myself with perfume. Then they said: 'Put that away, that's the most terrible smell I've ever smelled.' Then the teacher called the police."

The policeman didn't have far to come. He patrols the corridors of Sarah's school, Fulmore Middle in Austin, Texas. Like hundreds of schools in the state, and across large parts of the rest of the US, Fulmore Middle has its own police force with officers in uniform who carry guns to keep order in the canteens, playgrounds and lessons. Sarah was taken from class, charged with a criminal misdemeanour and ordered to appear in court.

Each day, hundreds of schoolchildren appear before courts in Texas charged with offences such as swearing, misbehaving on the school bus or getting in to a punch-up in the playground. Children have been arrested for possessing cigarettes, wearing "inappropriate" clothes and being late for school.

In 2010, the police gave close to 300,000 "Class C misdemeanour" tickets to children as young as six in Texas for offences in and out of school, which result in fines, community service and even prison time. What was once handled with a telling-off by the teacher or a call to parents can now result in arrest and a record that may cost a young person a place in college or a job years later.

"We've taken childhood behaviour and made it criminal," said Kady Simpkins, a lawyer who represented Sarah Bustamantes. "They're kids. Disruption of class? Every time I look at this law I think: good lord, I never would have made it in school in the US. I grew up in Australia and it's just rowdy there. I don't know how these kids do it, how they go to school every day without breaking these laws."

The British government is studying the American experience in dealing with gangs, unruly young people and juvenile justice in the wake of the riots in England. The UK's justice minister, Crispin Blunt, visited Texas last September to study juvenile courts and prisons, youth gangs and police outreach in schools, among other things. But his trip came at a time when Texas is reassessing its own reaction to fears of feral youth that critics say has created a "school-to-prison pipeline". The Texas supreme court chief justice, Wallace Jefferson, has warned that "charging kids with criminal offences for low-level behavioural issues" is helping to drive many of them to a life in jail.

The Texas state legislature last year changed the law to stop the issuing of tickets to 10- and 11-year-olds over classroom behaviour. (In the state, the age of criminal responsibility is 10.) But a broader bill to end the practice entirely – championed by a state senator, John Whitmire, who called the system "ridiculous" – failed to pass and cannot be considered again for another two years.

Even the federal government has waded in, with the US attorney general, Eric Holder, saying of criminal citations being used to maintain discipline in schools: "That is something that clearly has to stop."

As almost every parent of a child drawn in to the legal labyrinth by school policing observes, it wasn't this way when they were young.

The emphasis on law and order in the classroom parallels more than two decades of rapid expansion of all areas of policing in Texas in response to misplaced fears across the US in the 1980s of a looming crime wave stoked by the crack epidemic, alarmist academic studies and the media.

"It's very much tied in with some of the hyperbole around the rise in juvenile crime rate that took place back in the early 90s," said Deborah Fowler, deputy director of Texas Appleseed, an Austin legal rights group, and principal author of a 200-page study of the consequences of policing in Texas schools. "They ushered in tough, punitive policies. It was all part of the tough-on-crime movement."

Part of that included the passing of laws that made the US the only developed country to lock up children as young as 13 for life without the possibility of parole, often as accomplices to murders committed by an adult.

As the hand of law and order grew heavier across Texas, its grip also tightened on schools. The number of school districts in the state with police departments has risen more than 20-fold over the past two decades.

"Zero tolerance started out as a term that was used in combating drug trafficking and it became a term that is now used widely when you're referring to some very punitive school discipline measures. Those two policy worlds became conflated with each other," said Fowler.

In the midst of that drive came the 1999 Columbine high school massacre, in which two students in Colorado shot dead 12 other pupils and a teacher before killing themselves. Parents clamoured for someone to protect their children and police in schools seemed to many to be the answer.

But most schools do not face any serious threat of violence and police officers patrolling the corridors and canteens are largely confronted with little more than boisterous or disrespectful childhood behaviour.

"What we see often is a real overreaction to behaviour that others would generally think of as just childish misbehaviour rather than law breaking," said Fowler. Tickets are most frequently issued by school police for "disruption of class", which can mean causing problems during lessons but is also defined as disruptive behaviour within 500ft (150 metres) of school property such as shouting, which is classified as "making an unreasonable noise".

Among the more extreme cases documented by Appleseed is of a teacher who had a pupil arrested after the child responded to a question as to where a word could be found in a text by saying: "In your culo (arse)", making the other children laugh. Another pupil was arrested for throwing paper aeroplanes.

Students are also regularly fined for "disorderly behaviour", which includes playground scraps not serious enough to warrant an assault charge or for swearing or an offensive gesture. One teenage student was arrested and sent to court in Houston after he and his girlfriend poured milk on each other after they broke up. Nearly one third of tickets involve drugs or alcohol. Although a relatively high number of tickets – up to 20% in some school districts – involve charges over the use of weapons, mostly the weapons used were fists.

The very young are not spared. According to Appleseed, Texas records show more than 1,000 tickets were issued to primary schoolchildren over the past six years (although these have no legal force at that age). Appleseed said that "several districts ticketed a six-year-old at least once in the last five years".

Fines run up to $500. For poorer parents, the cost can be crippling. Some parents and students ignore the financial penalty, but that can have consequences years down the road. Schoolchildren with outstanding fines are regularly jailed in an adult prison for non-payment once they turn 17. Stumping up the fine is not an end to the offending student's problems either. A class-C misdemeanour is a criminal offence.

"Once you pay it, that's a guilty plea and that's on your record," said Simpkins. "In the US we have these astronomical college and university expenses and you go to fill out the application to get your federal aid for that and it says have you ever been arrested. And there you are, no aid."

In Austin, about 3% of the school district's 80,000 pupils were given criminal citations in the 2007/8 school year, the last date for which figures are available. But the chances of a teenager receiving a ticket in any given year are much higher than that because citations are generally issued to high-school pupils, not those in kindergarten or primary school.

The result, says the Appleseed report, is that "school-to-prison pipeline" in which a high proportion of children who receive tickets and end up in front of a court are arrested time and again because they are then marked out as troublemakers or find their future blighted by a criminal record.

From her perch on the bench in an Austin courtroom, Judge Jeanne Meurer has spent close on 30 years dealing with children hauled up for infractions, some serious, others minor. Some of the difficulties faced by teachers can be seen as Meurer decides whether a parade of children should be released to await trial or held in custody. Meurer switches between motherly and intimidating depending on what she makes of the child before her.

"Some of them are rough kids," she said. "I've been on the bench 30 years and you used to never have a child cuss you out like you do now. I appreciate the frustrations that adults have in dealing with children who seem to have no manners or respect. But these are our future. Shouldn't we find a tool to change that dynamic versus just arresting them in school and coming down with the hard criminal justice hammer?"

Many of those who appear in front of Meurer have learning problems. Children with disabilities are particularly vulnerable to the consequences of police in schools. Simpkins describes the case of a boy with attention deficit disorder who as a 12-year-old tipped a desk over in class in a rage. He was charged with threatening behaviour and sent to a juvenile prison where he was required to earn his release by meeting certain educational and behavioural standards.

"But he can't," she said. "Because of that he is turning 18 within the juvenile justice system for something that happened when he was 12. It's a real trap. A lot of these kids do have disabilities and that's how they end up there and can't get out. Instead of dealing with it within school system like we used to, we have these school police, they come in and it escalates from there."

Sometimes that escalation involves force. "We had one young man with an IQ well below 70 who was pepper-sprayed in the hallway because he didn't understand what the police were saying," said Simpkins. "After they pepper-sprayed him he started swinging his arms around in pain and he hit one of the police officers – it's on video, his eyes were shut – and they charged him with assault of a public servant. He was 16. He was charged with two counts of assault of a public servant and he is still awaiting trial. He could end up in prison."

Austin's school police department is well armed with officers carrying guns and pepper spray, and with dog units on call for sniffing out drugs and explosives.

According to the department's records, officers used force in schools more than 400 times in the five years to 2008, including incidents in which pepper spray was fired to break up a food fight in a canteen and guns were drawn on lippy students.

In recent months the questionable use of force has included the tasering of a 16-year-old boy at a high school in Seguin, Texas, after "he refused to cooperate" when asked why he wasn't wearing his school identification tag. He then used "abusive language". The police said that when an officer tried to arrest the boy, he attempted to bite the policeman. The youth was charged with resisting arrest and criminal trespass even though the school acknowledges he is a student and was legitimately on the grounds.

Such cases are not limited to Texas. In one notorious instance in California, a school security officer broke the arm of a girl he was arresting for failing to clear up crumbs after dropping cake in the school canteen. In another incident, University of Florida campus police tasered a student for pressing Senator John Kerry with an awkward question at a debate after he had been told to shut up.

Sometimes the force is deadly. Last week, Texas police were accused of overreacting in shooting dead a 15-year-old student, Jaime Gonzalez, at a school in Brownsville after he pointed an air gun, which resembled a real pistol, at them outside the principal's office. The boy's father, also called Jaime, said the police were too quick to shoot to kill when they could have wounded him or used another means to arrest him. "If they would have tased him all this wouldn't have happened," he told the Brownsville Herald. "Like people say there's been stand-offs with people that have hostages for hours … But here, they didn't even give I don't think five minutes. No negotiating." The police say Gonzalez defied orders to put the gun down.

Meurer says she is not against police in schools but questions whether officers should regard patrolling the playground the same way they go about addressing crime on the streets.

"When you start going overboard and using laws to control non-illegal behaviour – I mean if any adult did it it's not going to be a violation – that's where we start seeing a problem," she says. "You've gradually seen this morphing from schools taking care of their own environments to the police and security personnel, and all of a sudden it just became more and more that we were relying on law enforcement to control everyday behaviour."

Chief Brian Allen, head of the school police department for the Aldine district and president of the Texas school police chiefs' association, is having none of it.

"There's quite a substantial number of students that break the law. In Texas and in the US, if you're issued a ticket, it's not automatically that you're found guilty. You have an opportunity to go before the judge and plead your case. If you're a teacher and a kid that's twice as big as you comes up and hits you right in the face, what are you going to do? Are you going to use your skills that they taught you or are you going to call a police officer?"

But Allen concedes that the vast majority of incidents in which the police become involved are for offences that regarded as little more than misbehaviour elsewhere.

"Just like anything else, sometimes mistakes are made." he said. "Each circumstance is different and there's no set guideline. There's also something called officer discretion. If you take five auto mechanics and ask them to diagnose the problem of a vehicle, you'll come up with five different solutions. If you ask five different doctors to diagnose a patient, a lot of times you'll have five different diagnoses. Conversely, if you ask five different police officers if they would write a ticket or not for the same offence, you possibly have five different answers."

Jennifer Rambo (left) and her daughter Sarah Bustamentes, who was charged with 'disrupting class'. Photograph: Chris McGreal

Parents who have been sucked into the system, such as Jennifer Rambo, the mother of Sarah Bustamantes, wonder what happened to teachers taking responsibility for school discipline.

"I was very upset at the teacher because the teacher could have just stopped it. She could have said: OK class, that's enough. She could have asked Sarah for her perfume and told her that's inappropriate, don't do that in class. But she did none of that. She called the police," she says.

Politicians and civil liberties groups have raised the same question, asking if schools are not using the police to shift responsibility, and accountability, for discipline.

"Teachers rely on the police to enforce discipline," says Simpkins. "Part of it is that they're not accountable. They're not going to get into trouble for it. The parent can't come in and yell at them. They say: it's not us, it's the police."

That view is not shared by an Austin teacher who declined to be named because he said he did not want to stigmatise the children in his class.

"There's this illusion that it's just a few kids acting up; kids being kids. This is not the 50s. Too many parents today don't control their children. Their fathers aren't around. They're in gangs. They come in to the classroom and they have no respect, no self-discipline. They're doing badly, they don't want to learn, they just want to disrupt. They can be very threatening," he says. "The police get called because that way the teacher can go on with teaching instead of wasting half the class dealing with one child, and it sends a message to the other kids."

The Texas State Teachers Association, the state's main teachers union, did not take a position on ticketing at the recent debate in the legislature over Whitmire's proposal to scrap it. But the association's Clay Robison says that most teachers welcome the presence of police in schools.

"Obviously it looks as if some police officers are overreacting at some schools. I'm a parent and I wouldn't want my 17-year-old son hauled in to court if he and another student got in to an argument in a cafeteria. Police officers need to exercise a little bit of common sense but the police are what they are. They enforce the law," he says. "At the same time, years ago, at a school in one of the better neighbourhoods of Austin, a teacher was shot to death in his classroom. It's still a very rare occurrence but it does happen. Anything that increases the security of the teacher is good so they don't have to worry about personal safety and they can concentrate on teaching the kids. We get complaints from some teachers that the police aren't aggressive enough at moving against some of the older juveniles, those that they feel actually do pose a danger to the teachers or the other students."

Because of Sarah Bustamentes's mental disorders, a disability rights group took up her case and after months of legal battles prosecutors dropped the charges. Ask her how she feels about police in schools after her experience and she's equivocal.

"We need police in school. In my school it can get physical and it can turn out very bad," she says. "But they should stop issuing tickets. Only for physical stuff or bullying. Not what you do in class."