a legal challenge on whether Holyrood has the power to hold an independence referendum without the UK Government's permission.Neale Hanvey, who was readmitted to the party in May after being suspended for sharing an antisemitic image on social media, is among more than 4,000 backers of the People's Action on Section 30.Powers to hold a legally-binding referendum are reserved to Westminster under terms of the devolution settlement and can only be loaned them to Holyrood under a legal mechanism