5 Live Investigates has seen new evidence that hundreds of vulnerable children with Special Educational Needs are being injured whilst being restrained by teachers and classroom assistants. Physical and mechanical restraint techniques can be used against children as young as four without schools having to report it to anyone - even parents. But after 5 Live Investigates reported on this in 2017, the Government promised to introduce strict new guidelines detailing how restraint techniques should be used safely. Two years on and nothing has happened. Today the Children's Commissioners of Scotland, Wales and Northern Ireland have asked the United Nations to investigate the use of restraint. Photo credit: crossstudio\Getty