Downing Street’s plan to ban the glorifying of terrorism risks criminalising “supporters of the suffragettes, Nelson Mandela, or even the crowd at Murrayfield belting out Flower of Scotland”, a former independent reviewer of terror legislation has warned. A range of proposals has been floated by No 10 in the wake of the Armistice Day protests, where members of far-right organisations assaulted police officers and some participants on the pro-Palestine march held antisemitic placards. Law changes being examined by the government in response to the scenes that unfolded on Saturday will reportedly include tightening the law on glorifying terrorists such as the gunmen of Hamas who killed 1,200 people in Israel and took more than 200 people hostage on 7 October. After the murder of 52 people in London by suicide bombers in 2005, a prohibition on glorifying terrorism was introduced but it was tightly defined as statements that were “indirectly encouraging the commission or preparation of acts of terrorism”. David Anderson KC, who was the independent reviewer of terrorism legislation between 2011 and 2017, said efforts to broaden the scope of the law could have unintended consequences, as terrorism was defined in the statute books without historical or geographical bounds. Lord Anderson said: “Some of the proposed changes will no doubt be controversial, particularly in the House of Lords – but the Commons is likely to have the final say. “The prohibition on glorifying terrorism was introduced after the 7/7 attacks in London, but watered down during parliamentary debates so that it bites only if people could reasonably infer that there is an encouragement to emulate the conduct being glorified. “Because terrorism is defined without geographical or historical limits, it was pointed out that a straightforward prohibition on glorification could have criminalised supporters of the suffragettes, Nelson Mandela, or even the crowd at Murrayfield [rugby stadium, Edinburgh] belting out [the anthem] Flower of Scotland. “While no one suggests that these people would actually be prosecuted, it is dangerous in principle to legislate for criminal offences that are far broader than the conduct to which they are actually directed. We will have to see whether the government can find the solution that eluded Tony Blair.” Lord Carlile, who was the independent reviewer of terrorism legislation at the time the 2006 Terrorism Act was enacted, said the current police powers relating to hate speech and glorifying terrorism were sufficient and the government in its “parlous state” would struggle to get changes through the House of Lords. He said: “I think that amending the law is what would occur on the ‘something has to be done’ principle, to try and meet a perceived need.” He added that it was up to the police to know the law. “There are a number of things on those marches that may well require a response,” he said. “For example, if people are singing ‘from the river to the sea’. I would be surprised if they did not know, having decided to go on the march, that what they were singing is an old trope, which is about driving the Jews out of Israel from the river to the sea, the Mediterranean. And so, one might in certain circumstances, depending on the level of aggression, I think people should be prosecuted for hate speech.” It is understood that the current independent reviewer of terrorism legislation shares Anderson’s concerns. Ministers are likely to be lobbied to maintain a tight definition when it comes to prohibiting the glorifying of terrorism. One solution would be to amend section 13 of the 2006 Terrorism Act, which prohibits the act of wearing clothing or carrying or displaying articles “in public in such a way or in such circumstances as to arouse reasonable suspicion that an individual is a member or supporter of the proscribed organisation”. Ministers would broaden out what it means to be a “supporter” by including those who glorify a specific terrorist act by a proscribed group. The solution is unlikely to satisfy some on the government backbenches, including the former home secretary Suella Braverman, raising the potential for a major row within the Conservative party as well as with rights campaigners. Other government proposals include amending section 13 of the Public Order Act under which Sir Mark Rowley, the commissioner of the Metropolitan police, had been urged to ban Saturday’s pro-Palestine march. Under section 13 of the 1986 Public Order Act, a chief constable can apply to the home secretary to prohibit public processions to avoid serious public disorder where the imposition of conditions on the procession will not suffice. John Woodcock, a former Labour MP who was ennobled as Lord Walney in 2020, has been reviewing the law in his role as the government’s independent adviser on political violence and disruption. He has been examining the threshold for banning marches and is expected to back an amendment that took into consideration the wider impact marches might have on “public security”, although there will be concerns that a wide definition will overly restrict the right to free speech.