MPs who have been arrested for serious violent or sexual offences face bans from the parliamentary estate under rules approved by just one vote. The House of Commons voted by 170 to 169 on Monday night to toughen up a proposal put forward by the government, which would have only applied to MPs who have been formally charged. It means that if an MP has been arrested for a violent or sexual offence, a Commons panel will decide whether to bar them from the parliamentary estate. MPs were given a free vote on the proposals. The Commons leader, Penny Mordaunt, said ahead of the vote that the measures would “improve standards of behaviour and safeguarding”. Lucy Powell, the shadow Commons leader, said during the debate that the measures were “long overdue”. “Issues of serious wrongdoing or harassment or bad culture in workplaces have been a constant cloud over this place,” Powell told the Commons. “The headlines bring the entire house into disrepute and add to the erosion of trust in parliament and in politicians.” Under the new system, a risk assessment will be triggered when Commons authorities are alerted by police that an MP has been arrested for a violent or sexual offence. A panel, including senior MPs, will decide whether the MP under investigation poses a threat and should be barred from attending parliament. They will also decide whether to ban the MP in question from Commons-funded travel in the UK or abroad. MPs banned from the estate will continue to be able to vote by applying for a proxy. The proposals have been under discussion for more than a year and were developed by the House of Commons commission, a cross-party group of senior MPs including Mordaunt and Powell. There was no vote on the final motion so the measures passed as amended. The commission had originally recommended banning MPs earlier on during a criminal investigation, probably at the point of arrest. But in March ministers diluted the proposals to mean MPs can only be banned from parliament if they have been charged with a serious crime. The move was a response to a backlash from Tory backbenchers who argued that it was wrong to ban MPs from the parliamentary estate on the basis of allegations. Natalie Elphicke, the former Conservative MP who defected to Labour this month, was among those who backed the amendment by Liberal Democrat MP Wendy Chamberlain to toughen up the measures. Her defection has been controversial partly because she supported her ex-husband and predecessor as MP, Charlie Elphicke, after he was convicted for sexual assault. Jenny Symmons, who chairs the GMB branch for parliamentary staffers, said: “This is a huge win for MPs’ staff. It’s a small ask that people going about their jobs in parliament are able to do so without the lingering threat of sexual assault, but sadly that has been the reality.” Monday night’s vote reverted the measures to the form that the commission had originally proposed. It came after the Labour backbencher Jess Phillips called for the measures to be toughened. During the debate, she said she had spoken to two women on Monday who were raped by members of parliament. She read out a statement from one of them saying: “The exclusion at the point of charge sends a clear message to victims that not only will we not investigate unless a victim goes to the police, but we won’t act unless they’re charged – which happens in less than 1% of cases.” Another Labour backbencher, Stella Creasy, said the measures would stop “cosy wrap-ups with the whips office to try and manage situations” and formalise the process of excluding MPs. “We don’t protect the victims, we protect the perpetrators. Every political party needs to look itself in the eye,” she said. Jacob Rees-Mogg, a former Commons leader, said the proposals were an “extraordinary power grab” and argued that the exclusion of any MP should be voted on by the whole of the Commons as that was its “most ancient constitutional right”. Before this week, parliamentary authorities had no power to ban MPs accused of serious criminal wrongdoing from the estate. In some cases MPs have volunteered to stay away pending investigation after being strongly advised by their party whips to do so.