A legal challenge to the way techniques for restraint are used on young people in secure training centres is to be heard in the High Court tomorrow.

Secure training centres (STCs) are privately run prisons that hold young offenders deemed too vulnerable to be held in Prison Service-run young offender institutions.

Until earlier this year the rules for the use of restraint within STCs were different from the rules governing young offender institutions.

Within STCs restraint could only be used as a last resort, and to prevent injury or damage. In young offender institutions it could be used for the broader purpose of ensuring “good order and discipline”.

However on 6 July the Ministry of Justice brought in legislation to standardise the rules. Campaigners argue this has increased the potential for restraint to be used in STCs.

The test case is being brought on behalf as a child known as AC, and is backed by bereavement charity Inquest.

Deborah Coles, the co-director of Inquest, said: “In our view this change amounts to state sanctioned child abuse against some of society’s most vulnerable children.

“We fear it will lead to more restraint, damage and harm to children and ultimately more deaths.”