Throughout Pakistan, thousands of children are locked inside police cells or overcrowded jails, victims of a justice system that treats the very young much the same as adults.
Child prisoners are brought to court in chains, against international law
Kids as young as seven can spend years behind bars - before the courts have even decided if they are innocent or guilty.
"They are not taken seriously because children have no voice," says Hina Jilani, a human rights lawyer and activist.
"The kind of children who get arrested are totally vulnerable because of lack of power and lack of resources. And that's why a lot of them have been subjected to illegalities."
Handcuffed and chained
Each morning, amid the chaos of Karachi's packed main court, police vans pull up in the dusty courtyard and dozens of boys - some as young as 12 - clamber out.
Although Pakistani law forbids the use of chains for juveniles, these boys are handcuffed and attached to one another with a heavy iron chain.
The majority of child prisoners are acquitted when they finally reach court
And despite the fact that around half Pakistan's population is under 18, the country has only one juvenile court. Elsewhere, children are tried in adult courts - in breach of international law.
Supreme court lawyer Zia Awan says children are at risk from the moment they are taken into custody.
"The treatment with the juvenile prisoners is very alarming in our country," Mr Awan said.
Beaten with batons
His claim that torture is widespread is backed up by an independent NGO investigation which found that 70% of children who come into contact with the police are abused in some way.
"It's horrifying. There are beatings, or sometimes even sexual abuse. They are kept like slaves. Inside the police station, they are being tortured. All things aside from electric shocks are being used."
This includes beatings with leather whips, or being hung upside down to extract confessions.
"At the police station they beat me - four of them set about me with batons and they just kept beating me," said Khadim, one boy who agreed to talk as long as his real name was not used.
"They kept asking me for information, and when I couldn't tell them anything, they beat me. They only stopped because we paid them off. We gave the officer in charge a month's wages to stop the beatings."
At the time, Khadim was only 14, and both he and his older brother were charged with stealing - but it was days before the police notified their parents.
Although that is a violation of the law, it is not at all unusual.
Retired judge Nasir Zahed, who has been working at Karachi's juvenile jail to improve the lives of youngsters, said that of 500 inmates, only 30 are convicts - the other 470 are under-trial prisoners.
"They arrest the juveniles, keep them in custody, one year, two years or three years," he said.
"Then they release them or acquit them on account of the fact that there was no evidence."
Elsewhere, children endure much greater hardship.
In some places they are herded together in stifling barracks, locked up for most of the day, with concrete slabs for beds, appalling sanitation and the constant threat of disease.
And with most children imprisoned under the same roof as hardened adult criminals, they are easy prey.
Children from the most poverty-stricken areas are most affected
"They conducted a raid in Hyderabad central jail some years ago, and found 50 children in jail for petty crimes who had been sexually abused because they were kept with the adult prisoners," supreme court lawyer Zia Awan said.
"In the whole of Pakistan there is not a single facility for female juveniles. They are all kept with women who are drug addicts or drug dealers or maybe murderers."
But it is difficult to assess the full impact of this, because there is no effective monitoring.
And human rights lawyer Hina Jilani said children are increasingly being sent to prison as fall guys for adult criminals, who use them to do their dirty work.
"The use of children for criminal activity is on the rise, because the ones who are using them are enjoying impunity," she said.
"The children, who are being used, are the ones who get penalised."
But the convicted children face lengthy sentences - often with compulsory labour. NGOs have reported that jail terms of 10 years or more are common, irrespective of a child's crime.
Zia Awan worries about the consequences of such an uncaring system - both for the children involved and the whole of society.
"Trials are being delayed, they are not having contact with their families, legal aid is not being provided by the state, and then the children who are in prison are not being properly rehabilitated," he said.
"When they come out they end up in some mafia syndicate... I think we have to see that these are our children. And these are time bombs."