A union has launched legal action against Ofsted over plans to change the way schools are inspected. The NAHT, which represents school leaders, says its members haven't been adequately consulted - and the reforms could have an impact on the mental health of staff. Last year, it was announced one-word inspections would be scrapped, with schools graded across eight to 10 areas on report cards instead. Each grade would be on a colour-coded, five-point scale - ranging from red meaning causing concern, to dark green for exemplary. Image: How the new report card would work. Pic: Ofsted The union fears this will only exacerbate the pressure facing headteachers - and at its annual conference today, a vote will be held on opposing the new scheme. If approved, the motion would call for all "legal and industrial options" to be explored to protect the mental and physical health of school leaders and staff. Changes to the inspection process were proposed following the death of Ruth Perry, a headteacher in Reading. She took her own life in January 2023 after an Ofsted report downgraded Caversham Primary from outstanding to inadequate. Image: Ruth Perry's family said she took her own life after an Ofsted report Earlier this week, Ms Perry's sister Julia Waters signed an open letter to Education Secretary Bridget Phillipson, which urged the education watchdog to delay these reforms. Prof Waters said: "This new system, proposed for itself by Ofsted, could be worse than the flawed and dangerous process it replaces." Read more from Sky News: Reform's political earthquake is now shaking our political system Ukraine troops to join British forces for VE Day procession NAHT general secretary Paul Whiteman has claimed that the health and wellbeing of staff has been "lost" during the consultation process. He warned: "School leaders are deeply concerned that the new report cards could result in an even worse system than before, with a potentially disastrous impact on workload, wellbeing and retention. "We have tried engaging with Ofsted and explaining this, but so far these concerns have fallen on deaf ears. We have been left with little choice other than to pursue this action." Be the first to get Breaking News Install the Sky News app for free An Ofsted spokeswoman said: "Supporting the mental health of those we inspect is an important part of the development of our proposals and we are already hearing positive feedback through our inspection tests. "Our legal team have responded robustly to NAHT. Their suggested claims are plainly untenable. If legal action is launched, we will resist and seek costs."