MPs have voted down controversial proposals introduced by the leader of the House of Commons, Jacob Rees-Mogg, that would have allowed them to debate complaints about serious bullying and harassment. In an open letter seen by the Guardian, past and present parliamentary staff, union leaders, MPs and women’s groups had accused Rees-Mogg of undermining a new independent system designed to prevent bullying and sexual harassment in parliament, by allowing MPs to debate serious sanctions made by a new independent expert panel (IEP). But on Tuesday evening, an amendment tabled by Labour MP Chris Bryant, which ruled out debating complaints against MPs in the chamber, passed by five votes – to the delight of parliamentary staffers and campaigners. MPs were given a free vote, but Tory whips told their MPs that the chief whip would be voting against the Bryant amendment and for the motion in the name of the leader of the house. However, the amendment found favour on both sides of the house. New Tory MP and former employment law barrister Laura Farris said: “Any form of process which invites members to speak up for colleagues against a background of party allegiance and personal loyalties is fundamentally problematic.” Former Commons leader Andrea Leadsom argued that allowing a debate, even with constraints, would “result in a complainant feeling re-victimised”. Labour’s Jess Phillips said allowing debates would stop victims from coming forward, while fellow Labour MP Meg Hillier raised concerns about a “bully pulpit” being used in the Commons. MPs voted in favour of supporting the creation of an independent panel of experts to deal with allegations against them. The eight-member panel will have the ability to investigate independently and impose sanctions including the suspension and exclusion of MPs in the most serious cases. The move was hailed as a “game-changer” by Amy Leversidge, assistant general secretary of the FDA civil service union. “All the staff who have lost their careers in the past will tonight feel so proud that they have spoken out and made a real difference,” she said. “People will finally be able to have their complaint determined fairly, and that’s a real win for everyone in parliament.” The introduction of an independent complaints procedure came more than 18 months after an independent inquiry by Dame Laura Cox revealed the scale of sexual harassment, intimidation and bullying in Westminster. Cox said the vast majority of abuse was targeted at women, whose careers had been blighted by a lack of action. Helen Pankhurst of the Centenary Action Group, which organised the letter in opposition to the right to debate sanctions, said that thanks to the establishment of an independent complaints panel and the Bryant amendment, parliament was “a safer place” to work. “Both women and men must be able to exercise their right to take part in politics without fear of bullying, abuse and sexual harassment,” she said. “Today’s vote has taken us a step closer to achieving this right.” Emily Commander, a former Commons clerk who became the first to trigger a formal investigation into an MP’s conduct in 2012, tweeted: “I am so proud of my friends and former colleagues for making such a positive change to the procedures for tackling bullying and harassment in the House of Commons.”